Apparatus

ABSTRACT

[Object] To enable improving accuracy of decoding of a desired signal when multiplexing/multiple access is performed using power allocation. 
     [Solution] Provided is an apparatus including: a first transmission processing unit that generates transmission signal sequences of multiple power layers that are to be multiplexed using power allocation; and a second transmission processing unit that processes a transmission signal sequence of a power layer using an interleaver, a scrambler, or a phase coefficient corresponding to the power layer for each of one or more of the multiple power layers.

TECHNICAL FIELD

The present invention relates to an apparatus.

BACKGROUND ART

Non-orthogonal multiple access (NOMA) has been attracting attention as aradio access technology (RAT) for a fifth generation (5G) mobilecommunication system following Long Term Evolution (LTE)/LTE-Advanced(LTE-A). In orthogonal frequency-division multiple access (OFDMA) andsingle-carrier frequency-division multiple access (SC-FDMA), which areadopted in LTE, radio resources (e.g., resource blocks) are allocated tousers without overlap. These schemes are called orthogonal multipleaccess. In contrast, in non-orthogonal multiple access, radio resourcesare allocated to users with overlap. In non-orthogonal multiple access,signals of users interfere with each other, but a signal for each useris taken out by a high-accuracy decoding process at the reception side.Non-orthogonal multiple access, in theory, achieves higher cellcommunication capability than orthogonal multiple access.

One of radio access technologies classified into non-orthogonal multipleaccess is superposition coding (SPC) multiplexing/multiple access. SPCis a scheme in which signals to which different levels of power areallocated are multiplexed on at least partly overlapping radio resourcesin frequency and time. At the reception side, interference cancellationand/or iterative detection is performed for reception/decoding ofsignals multiplexed on the same radio resource.

For example, PTLs 1 and 2 disclose, as SPC or a technology equivalent toSPC, techniques for setting an amplitude (or power) that allowsappropriate demodulation/decoding. Moreover, for example, PTL 3discloses a technique for enhancing successive interference cancellation(SIC) for reception of multiplexed signals.

CITATION LIST Patent Literature

Patent Literature 1: JP 2003-78419A

Patent Literature 2: JP 2003-229835A

Patent Literature 3: JP 2013-247513A

DISCLOSURE OF INVENTION Technical Problem

For example, fading (e.g., fading of frequency selectivity and/or timeselectivity) is equally generated in multiple power layers multiplexedusing SPC. Accordingly, accuracy of decoding of signals (interferencesignal and desired signal) of the multiple power layers decreases withrespect to specific radio resources (e.g., frequency resources and/ortime resources). Further, interference cancellation accuracy alsodecreases, and thus residual interference increases due to a decrease inaccuracy of decoding of an interference signal with respect to thespecific radio resources. As a result, it may be difficult to correctlydecode a desired signal because residual interference increases andaccuracy of decoding of the desired signal decreases with respect to thespecific radio resources.

Accordingly, it is desirable to provide a system capable of improvingaccuracy of decoding of a desired signal when multiplexing/multipleaccess is performed using power allocation.

Solution to Problem

According to the present disclosure, there is provided an apparatusincluding: a first transmission processing unit that generatestransmission signal sequences of multiple power layers that are to bemultiplexed using power allocation; and a second transmission processingunit that processes a transmission signal sequence of a power layerusing an interleaver, a scrambler, or a phase coefficient correspondingto the power layer for each of one or more of the multiple power layers.

In addition, according to the present disclosure, there is provided anapparatus including: an acquisition unit that acquires a deinterleaver,a descrambler or a phase coefficient corresponding to each of at leastone power layer among multiple power layers that are to be multiplexedusing power allocation; and a reception processing unit that performs areception process using the deinterleaver, the descrambler or the phasecoefficient corresponding to each of the at least one power layer.

Advantageous Effects of Invention

According to the above-described present disclosure, it is possible toimprove decoding accuracy when multiplexing/multiple access is performedusing power allocation. Note that the effects described above are notnecessarily limitative. With or in the place of the above effects, theremay be achieved any one of the effects described in this specificationor other effects that may be grasped from this specification.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a first explanatory diagram for explaining an example of aprocess in a transmission device that supports SPC.

FIG. 2 is a second explanatory diagram for explaining an example of aprocess in a transmission device that supports SPC.

FIG. 3 is an explanatory diagram for explaining an example of a processin a reception device that performs interference cancellation.

FIG. 4 is a first explanatory diagram for explaining an example ofmultiplexing using SPC.

FIG. 5 is a first explanatory diagram for explaining an example ofmultiplexing using SPC.

FIG. 6 is an explanatory diagram for explaining an example of fading andresidual interference.

FIG. 7 is an explanatory diagram illustrating an example of a schematicconfiguration of a system according to an embodiment of the presentdisclosure.

FIG. 8 is a block diagram illustrating an example of a configuration ofa base station according to the embodiment.

FIG. 9 is a block diagram illustrating an example of a configuration ofa terminal device according to the embodiment.

FIG. 10 is an explanatory diagram for explaining an example of powerallocation to power layers.

FIG. 11 is a first explanatory diagram for explaining an example ofdecoding a signal according to a first embodiment.

FIG. 12 is a second explanatory diagram for explaining an example ofdecoding a signal according to a first embodiment.

FIG. 13 is a third explanatory diagram for explaining an example ofdecoding a signal according to a first embodiment.

FIG. 14 is a fourth explanatory diagram for explaining an example ofdecoding a signal according to a first embodiment.

FIG. 15 is an explanatory diagram for explaining a result of a firstsimulation related to interleaving.

FIG. 16 is an explanatory diagram for explaining a result of a secondsimulation related to interleaving.

FIG. 17 is a flowchart illustrating an example of a schematic flow of atransmission process of a base station according to the firstembodiment.

FIG. 18 is a flowchart illustrating an example of a schematic flow of areception process of a terminal device according to the firstembodiment.

FIG. 19 is a flowchart illustrating an example of a schematic flow of adecoding process for non-SPC.

FIG. 20 is a flowchart illustrating a first example of a schematic flowof a decoding process for SPC.

FIG. 21 is a flowchart illustrating an example of a schematic flow of adecoding process for non-SPC for a target layer.

FIG. 22 is a flowchart illustrating an example of a schematic flow of aninterference signal replica generation process for a target layer.

FIG. 23 is a flowchart illustrating a second example of a schematic flowof a decoding process for SPC.

FIG. 24 is a flowchart illustrating an example of a schematic flow of aparallel decoding process.

FIG. 25 is a flowchart illustrating an example of a schematic flow of aninterference signal replica generation process.

FIG. 26 is a sequence diagram illustrating a first example of aschematic flow of a process including a notification from a base stationto a terminal device.

FIG. 27 is a sequence diagram illustrating a second example of aschematic flow of a process including a notification from a base stationto a terminal device.

FIG. 28 is a sequence diagram illustrating a third example of aschematic flow of a process including a notification from a base stationto a terminal device.

FIG. 29 is an explanatory diagram for explaining a first example ofmultiplexing spatial layers and power layers.

FIG. 30 is an explanatory diagram for explaining a second example ofmultiplexing spatial layers and power layers.

FIG. 31 is a flowchart illustrating an example of a schematic flow of amultiplexing determination process according to a first modified exampleof the first embodiment.

FIG. 32 is a flowchart illustrating an example of a schematic flow ofanother selection process.

FIG. 33 is a flowchart illustrating an example of a schematic flow of atransmission power determination process according to the first modifiedexample of the first embodiment.

FIG. 34 is a flowchart illustrating an example of a schematic flow of atransmission process of a base station according to the first modifiedexample of the first embodiment.

FIG. 35 is an explanatory diagram for explaining an example of shift ofchannel variation in a frequency direction.

FIG. 36 is a flowchart illustrating an example of a schematic flow of atransmission process of a base station according to a second embodiment.

FIG. 37 is a flowchart illustrating an example of a schematic flow of areception process of a terminal device according to the secondembodiment.

FIG. 38 is an explanatory diagram for explaining an example of a processin a case of a combination of spatial multiplexing and multiplexingusing power allocation.

FIG. 39 is a block diagram illustrating a first example of a schematicconfiguration of an eNB.

FIG. 40 is a block diagram illustrating a second example of theschematic configuration of the eNB.

FIG. 41 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 42 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, (a) preferred embodiment(s) of the present disclosure willbe described in detail with reference to the appended drawings. In thisspecification and the appended drawings, structural elements that havesubstantially the same function and structure are denoted with the samereference numerals, and repeated explanation of these structuralelements is omitted.

Furthermore, in this specification and the appended drawings, elementshaving substantially the same functional configuration may bediscriminated by putting different letters after the same referencenumeral. For example, elements having substantially the same functionalconfiguration are discriminated as terminal devices 200A, 200B and 200Cas necessary. However, when it is unnecessary to specially discriminatebetween multiple elements having substantially the same functionalconfiguration, only the same reference numeral is attached thereto. Forexample, when it is unnecessary to specially discriminate between theterminal devices 200A, 200B, and 200C, the terminal devices are simplycalled a terminal device 200.

Note that description will be provided in the following order.

1. SPC

2. Technical problem3. Schematic configuration of communication system4. Configuration of each device4.1. Configuration of base station4.2. Configuration of terminal device

5. First Embodiment

5.1. Technical features5.2. Process flow5.3. First modified example5.4. Second modified example

6. Second Embodiment

6.1. Technical features6.2. Process flow6.3. Modified example

7. Application

7.1. Application example with regard to base station7.2. Application example with regard to terminal device

8. Conclusion 1. SPC

Firstly described with reference to FIGS. 1 to 3 are processes andsignals of SPC.

(1) Process in Each Device (a) Process in Transmission Device

FIGS. 1 and 2 are explanatory diagrams for explaining an example of aprocess in a transmission device that supports SPC. According to FIG. 1,for example, bit streams (e.g., transport blocks) of a user A, a user B,and a user C are processed. For each of these bit streams, someprocesses (e.g., cyclic redundancy check (CRC) encoding, forward errorcorrection (FEC) encoding, rate matching, and scrambling/interleaving,as illustrated in FIG. 2) are performed and then modulation isperformed. Further, layer mapping, power allocation, precoding, SPCmultiplexing, resource element mapping, inverse discrete Fouriertransform (IDFT)/inverse fast Fourier transform (IFFT), cyclic prefix(CP) insertion, digital-to-analog and radio frequency (RF) conversion,and the like are performed.

In particular, in power allocation, power is allocated to signals of theuser A, the user B, and the user C, and in SPC multiplexing, the signalsof the user A, the user B, and the user C are multiplexed.

(b) Process in Reception Device

FIG. 3 is an explanatory diagram for explaining an example of a processin a reception device that performs interference cancellation. Accordingto FIG. 4, for example, RF and analog-to-digital conversion, CP removal,discrete Fourier transform (DFT)/fast Fourier transform (FFT), jointinterference cancellation, equalization, decoding, and the like areperformed. This provides bit streams (e.g., transport blocks) of theuser A, the user B, and the user C.

(2) Transmission Signals and Reception Signals (a) Downlink

Next, downlink transmission signals and reception signals when SPC isadopted will be described. Assumed here is a multi-cell system ofheterogeneous network (HetNet), small cell enhancement (SCE), or thelike.

An index of a cell to be in connection with a target user u is denotedby i, and the number of transmission antennas of a base stationcorresponding to the cell is denoted by N_(TX,i). Each of thetransmission antennas may also be called a transmission antenna port. Atransmission signal from the cell i to the user u can be expressed in avector form as below.

$\begin{matrix}{s_{i,u} = {\begin{bmatrix}s_{i,u,0} \\\vdots \\s_{i,u,{N_{{TX},i} - 1}}\end{bmatrix} = {W_{i,u}P_{i,u}x_{i,u}}}} & \left\lbrack {{Math}.\mspace{11mu} 1} \right\rbrack \\{W_{i,u} = \begin{bmatrix}w_{i,u,0,0} & \ldots & w_{i,u,0,{N_{{SS},u} - 1}} \\\vdots & \ddots & \vdots \\w_{i,u,{N_{{TX},i} - 1},0} & \ldots & w_{i,u,{N_{{TX},i} - 1},{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 2} \right\rbrack \\{P_{i,u} = \begin{bmatrix}P_{i,u,0,0} & \ldots & P_{i,u,0,{N_{{SS},u} - 1}} \\\vdots & \ddots & \vdots \\P_{i,u,{N_{{SS},u} - 1},0} & \ldots & P_{i,u,{N_{{SS},u} - 1},{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 3} \right\rbrack \\{x_{i,u} = \begin{bmatrix}x_{i,u,0} \\\vdots \\x_{i,u,{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 4} \right\rbrack\end{matrix}$

In the above expressions, N_(SS,u) denotes the number of spatialtransmission streams for the user u. Basically, N_(SS,u) is a positiveinteger equal to or less than N_(TX,i). A vector x_(i,u) is a spatialstream signal to the user u. Elements of this vector basicallycorrespond to digital modulation symbols of phase shift keying (PSK),quadrature amplitude modulation (QAM), or the like. A matrix W_(i,u) isa precoding matrix for the user u. An element in this matrix isbasically a complex number, but may be a real number.

A matrix P_(i,u), is a power allocation coefficient matrix for the useru in the cell i. In this matrix, each element is preferably a positivereal number. Note that this matrix may be a diagonal matrix (i.e., amatrix whose components excluding diagonal components are zero) asbelow.

$\begin{matrix}{P_{i,u} = \begin{bmatrix}P_{i,u,0,0} & 0 & \ldots & 0 \\0 & P_{i,u,1,1} & \ddots & \vdots \\\vdots & \ddots & \ddots & 0 \\0 & \ldots & \ldots & P_{i,u,{N_{{SS},u} - 1},{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 5} \right\rbrack\end{matrix}$

If adaptive power allocation for a spatial stream is not performed, ascalar value P_(i,u) may be used instead of the matrix P_(i,u).

As well as the user u, another user v is present in the cell i, and asignal s_(i,v) of the other user v is also transmitted on the same radioresource. These signals are multiplexed using SPC. A signal s_(i) fromthe cell i after multiplexing is expressed as below.

$\begin{matrix}{s_{i} = {\sum\limits_{u^{\prime} \in U_{i}}\; s_{i,u^{\prime}}}} & \left\lbrack {{Math}.\mspace{11mu} 6} \right\rbrack\end{matrix}$

In the above expression, U_(i) denotes a set of users for whichmultiplexing is performed in the cell i. Also in a cell j (a cell thatserves as an interference source for the user u) other than a servingcell of the user u, a transmission signal s_(j) is generated similarly.Such a signal is received as interference at the user side. A receptionsignal r_(u) of the user u can be expressed as below.

$\begin{matrix}{r_{u} = {\begin{bmatrix}r_{u,0} \\\vdots \\r_{u,{N_{{RX},u} - 1}}\end{bmatrix} = {{\sum\limits_{i^{\prime}}\; {H_{u,i^{\prime}}s_{i^{\prime}}}} + n_{u}}}} & \left\lbrack {{Math}.\mspace{11mu} 7} \right\rbrack \\{H_{u,i} = \begin{bmatrix}h_{u,i,0,0} & \ldots & h_{u,i,0,{N_{{TX},i} - 1}} \\\vdots & \ddots & \vdots \\h_{u,i,{N_{{RX},u} - 1},0} & \ldots & h_{u,i,{N_{{RX},u} - 1},{N_{{TX},i} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 8} \right\rbrack \\{n_{u} = \begin{bmatrix}n_{u,0} \\\vdots \\n_{u,{N_{{RX},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 9} \right\rbrack\end{matrix}$

In the above expressions, a matrix H_(u,i) is a channel response matrixfor the cell i and the user u. Each element of the matrix H_(u,i) isbasically a complex number. A vector n_(u) is noise included in thereception signal r_(u) of the user u. For example, the noise includesthermal noise and interference from another system. The average power ofthe noise is expressed as below.

σ_(n,u) ²  [Math. 10]

The reception signal r_(u) can also be expressed by a desired signal andanother signal as below.

$\begin{matrix}{r_{u} = {{H_{u,i}s_{i,u}} + {H_{u,i}{\sum\limits_{{v \in U_{i}},{v \neq u}}\; s_{i,v}}} + {\sum\limits_{j \neq i}\; {H_{u,j}{\sum\limits_{v \in U_{j}}\; s_{j,v}}}} + n_{u}}} & \left\lbrack {{Math}.\mspace{11mu} 11} \right\rbrack\end{matrix}$

In the above expression, the first term of the right side denotes adesired signal of the user u, the second term, interference in theserving cell i of the user u (called intra-cell interference, multi-userinterference, multi-access interference, or the like), and the thirdterm, interference from a cell other than the cell i (called inter-cellinterference).

When orthogonal multiple access (e.g., OFDMA or SC-FDMA) or the like isadopted, the reception signal can be expressed as below.

$\begin{matrix}{r_{u} = {{H_{u,i}s_{i,u}} + {\sum\limits_{j \neq i}\; {H_{u,j}\mspace{11mu} s_{j,v}}} + n_{u}}} & \left\lbrack {{Math}.\mspace{11mu} 12} \right\rbrack\end{matrix}$

In orthogonal multiple access, no intra-cell interference occurs, andmoreover, in the other cell j, a signal of the other user v is notmultiplexed on the same radio resource.

(b) Uplink

Next, uplink transmission signals and reception signals when SPC isadopted will be described. Assumed here is a multi-cell system ofHetNet, SCE, or the like. Note that the signs used for downlink will befurther used as signs denoting signals and the like.

A transmission signal that the user u transmits in the cell i can beexpressed in a vector form as below.

$\begin{matrix}{s_{i,u} = {\begin{bmatrix}s_{i,u,0} \\\vdots \\s_{i,u,{N_{{TX},u} - 1}}\end{bmatrix} = {W_{i,u}P_{i,u}x_{i,u}}}} & \left\lbrack {{Math}.\mspace{11mu} 13} \right\rbrack \\{W_{i,u} = \begin{bmatrix}w_{i,u,0,0} & \ldots & w_{i,u,0,{N_{{SS},u} - 1}} \\\vdots & \ddots & \vdots \\w_{i,u,{N_{{TX},u} - 1},0} & \ldots & w_{i,u,{N_{{TX},u} - 1},{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 14} \right\rbrack \\{P_{i,u} = \begin{bmatrix}P_{i,u,0,0} & \ldots & P_{i,u,0,{N_{{SS},u} - 1}} \\\vdots & \ddots & \vdots \\P_{i,u,{N_{{SS},u} - 1},0} & \ldots & P_{i,u,{N_{{SS},u} - 1},{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 15} \right\rbrack \\{x_{i,u} = \begin{bmatrix}x_{i,u,0} \\\vdots \\x_{i,u,{N_{{SS},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 16} \right\rbrack\end{matrix}$

In the above expressions, the number of transmission antennas is thenumber of transmission antennas of the user, N_(TX,u). As in downlink, amatrix P_(i,u), which is a power allocation coefficient matrix for theuser u in the cell i, may be a diagonal matrix.

In uplink, there is no case where a signal of a user and a signal ofanother user are multiplexed in the user; thus, a reception signal of abase station of the cell i can be expressed as below.

$\begin{matrix}{r_{i} = {\begin{bmatrix}r_{i,0} \\\vdots \\r_{i,{N_{{RX},i} - 1}}\end{bmatrix} = {{\sum\limits_{i^{\prime}}\; {\sum\limits_{u^{\prime} \in U_{i^{\prime}}}\; {H_{i^{\prime},u^{\prime}}s_{i^{\prime},u^{\prime}}}}} + n_{i}}}} & \left\lbrack {{Math}.\mspace{11mu} 17} \right\rbrack \\{H_{i,u} = \begin{bmatrix}h_{i,u,0,0} & \ldots & h_{i,u,0,{N_{{TX},u} - 1}} \\\vdots & \ddots & \vdots \\h_{i,u,{N_{{RX},i} - 1},0} & \ldots & h_{i,u,{N_{{RX},i} - 1},{N_{{TX},u} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 18} \right\rbrack \\{n_{i} = \begin{bmatrix}n_{i,0} \\\vdots \\n_{i,{N_{{RX},i} - 1}}\end{bmatrix}} & \left\lbrack {{Math}.\mspace{11mu} 19} \right\rbrack\end{matrix}$

It should be noted that in uplink, unlike in downlink, a base stationneeds to obtain all signals from a plurality of users in a cell bydecoding. Note also that a channel response matrix differs depending ona user.

When a focus is put on a signal transmitted by the user u, among uplinksignals in the cell i, a reception signal can be expressed as below.

$\begin{matrix}{r_{i,u} = {\begin{bmatrix}r_{i,u,0} \\\vdots \\r_{i,u,{N_{{RX},i} - 1}}\end{bmatrix} = {{H_{i,u}\mspace{11mu} s_{i,u}} + {\sum\limits_{{v \in U_{i}},{v \neq u}}\; {H_{i,v}\mspace{11mu} s_{i,v}}} + {\sum\limits_{j \neq i}\; {\sum\limits_{v \in U_{j}}\; {H_{i,v}\mspace{11mu} s_{j,v}}}} + n_{i}}}} & \left\lbrack {{Math}.\mspace{11mu} 20} \right\rbrack\end{matrix}$

In the above expression, the first term of the right side denotes adesired signal of the user u, the second term, interference in theserving cell i of the user u (called intra-cell interference, multi-userinterference, multi-access interference, or the like), and the thirdterm, interference from a cell other than the cell i (called inter-cellinterference).

When orthogonal multiple access (e.g., OFDMA or SC-FDMA) or the like isadopted, the reception signal can be expressed as below.

$\begin{matrix}{r_{i,u} = {{H_{i,u}\mspace{11mu} s_{i,u}} + {\sum\limits_{j \neq i}\; {H_{i,v}\mspace{11mu} s_{j,v}}} + n_{i}}} & \left\lbrack {{Math}.\mspace{11mu} 21} \right\rbrack\end{matrix}$

In orthogonal multiple access, no intra-cell interference occurs, andmoreover, in the other cell j, a signal of the other user v is notmultiplexed on the same radio resource.

2. TECHNICAL PROBLEM

Next, a technical problem according to an embodiment of the presentdisclosure will be described with reference to FIGS. 4 to 6.

For example, fading (e.g., fading of frequency selectivity and/or timeselectivity) is equally generated in multiple power layers multiplexedusing SPC. Accordingly, accuracy of decoding of signals of the multiplepower layers (an interference signal and a desired signal) decreaseswith respect to specific radio resources (e.g., frequency resourcesand/or time resources). Further, accuracy of interference cancellationalso decreases, and thus residual interference increases due to adecrease in accuracy of decoding of an interference signal with respectto the specific radio resources. As a result, it may be difficult tocorrectly decode a desired signal because residual interferenceincreases and accuracy of decoding of the desired signal decreases withrespect to the specific radio resources. A specific example with respectto this fact will be described below with reference to FIGS. 4 to 6.

FIGS. 4 and 5 are explanatory diagrams for explaining an example ofmultiplexing using SPC. Referring to FIG. 4, a base station 10, aterminal device 20A, and a terminal device 20B are illustrated. Forexample, the base station 10 multiplexes a power layer 0 and a powerlayer 1, transmits a signal to the terminal device 20A using the powerlayer 0, and transmits a signal to the terminal device 20B using thepower layer 1. In addition, referring to FIG. 5, power P₀ allocated tothe power layer 0 (a power layer corresponding to the terminal device20A) and power P₁ allocated to the power layer 1 (a power layercorresponding to the terminal device 20B) are illustrated. For example,in this manner, lower power is allocated to the power layer 0corresponding to the terminal device 20A (i.e., a terminal device havinglow path loss) closer to the base station 100. In addition, higher poweris allocated to the power layer 1 corresponding to the terminal device20B (i.e., a terminal device having high path loss) farther away fromthe base station 100. Further, the terminal device 20A may be a terminaldevice included in a main lobe of a directional beam, and the terminaldevice 20B may be a terminal device separated from the main lobe of thedirectional beam.

FIG. 6 is an explanatory diagram for explaining an example of fading andresidual interference. Referring to FIG. 6, received power 31 of thepower layer 0 in the terminal device 20A (i.e., received power of adesired signal) and received power 33 of the power layer 1 in theterminal device 20A (i.e., received power of an interference signal) areillustrated. In the power layer 0 and the power layer 1, significantfading is generated in radio resources 37A, 37B, 37C and 37D.Accordingly, with respect to the radio resources 37A, 37B, 37C and 37D,a burst error is generated during decoding of a signal (i.e.,interference signal) of the power layer 1 and accuracy of decoding ofthe signal of the power layer 1 decreases. Furthermore, interferencecancellation accuracy also decreases, and thus residual interference 35increases due to the decrease in the accuracy of decoding of the signalof power layer 1 with respect to the radio resources 37A, 37B, 37C and37D. In addition, accuracy of decoding of a signal (i.e., desiredsignal) of the power layer 0 decreases like the signal (i.e.,interference signal) of the power layer 1 with respect to the radioresources 37A, 37B, 37C and 37D. As a result, it may be difficult tocorrectly decode the signal (i.e., desired signal) of the power layer 0because the residual interference 35 increases and the accuracy ofdecoding of the signal (i.e., desired signal) of the power layer 0decreases with respect to the radio resources 37A, 37B, 37C and 37D.

Accordingly, it is desirable to provide a system capable of improvingdecoding accuracy when multiplexing/multiple access using powerallocation is performed.

3. SCHEMATIC CONFIGURATION OF SYSTEM

Now, a schematic configuration of a system 1 according to an embodimentof the present disclosure will be described with reference to FIG. 7.FIG. 7 is an explanatory diagram illustrating an example of theschematic configuration of the system 1 according to an embodiment ofthe present disclosure. According to FIG. 7, the system 1 includes abase station 100 and a terminal device 200. Here, the terminal device200 is also called a user. The user may also be called a user equipment(UE). Here, the UE may be a UE defined in LTE or LTE-A, or may generallyrefer to communication equipment.

(1) Base Station 100

The base station 100 is a base station of a cellular system (or mobilecommunication system). The base station 100 performs radio communicationwith a terminal device (e.g., the terminal device 200) located in a cell101 of the base station 100. For example, the base station 100 transmitsa downlink signal to the terminal device, and receives an uplink signalfrom the terminal device.

(2) Terminal Device 200

The terminal device 200 can perform communication in a cellular system(or mobile communication system). The terminal device 200 performs radiocommunication with a base station (e.g., the base station 100) of thecellular system. For example, the terminal device 200 receives adownlink signal from the base station, and transmits an uplink signal tothe base station.

(3) Multiplexing/Multiple Access

In particular, in the embodiment of the present disclosure, the basestation 100 performs radio communication with a plurality of terminaldevices by non-orthogonal multiple access. More specifically, the basestation 100 performs radio communication with a plurality of terminaldevices by multiplexing/multiple access using power allocation. Forexample, the base station 100 performs radio communication with theplurality of terminal devices by multiplexing/multiple access using SPC.

For example, the base station 100 performs radio communication with theplurality of terminal devices by multiplexing/multiple access using SPCin downlink. Specifically, for example, the base station 100 multiplexessignals to the plurality of terminal devices using SPC. In this case,for example, the terminal device 200 removes one or more other datasignals, as interference, from a multiplexed signal including a desiredsignal (that is, a signal to the terminal device 200), and decodes thedesired signal.

Note that the base station 100 may perform radio communication with theplurality of terminal devices by multiplexing/multiple access using SPCin uplink, instead of or together with downlink. In this case, the basestation 100 may decode a multiplexed signal including signalstransmitted from the plurality of terminal devices into the signals.

4. CONFIGURATION OF EACH DEVICE

Now, configurations of the base station 100 and the terminal device 200according to an embodiment of the present disclosure will be describedwith reference to FIGS. 8 and 9.

<4.1. Configuration of Base Station>

First, an example of the configuration of the base station 100 accordingto an embodiment of the present disclosure will be described withreference to FIG. 8. FIG. 8 is a block diagram illustrating the exampleof the configuration of the base station 100 according to an embodimentof the present disclosure. According to FIG. 8, the base station 100includes an antenna unit 110, a radio communication unit 120, a networkcommunication unit 130, a storage unit 140, and a processing unit 150.

(1) Antenna Unit 110

The antenna unit 110 radiates signals output by the radio communicationunit 120 out into space as radio waves. In addition, the antenna unit110 converts radio waves in the space into signals, and outputs thesignals to the radio communication unit 120.

(2) Radio Communication Unit 120

The radio communication unit 120 transmits and receives signals. Forexample, the radio communication unit 120 transmits a downlink signal toa terminal device, and receives an uplink signal from a terminal device.

(3) Network Communication Unit 130

The network communication unit 130 transmits and receives information.For example, the network communication unit 130 transmits information toother nodes, and receives information from other nodes. For example, theother nodes include another base station and a core network node.

(4) Storage Unit 140

The storage unit 140 temporarily or permanently stores a program andvarious data for operation of the base station 100.

(5) Processing Unit 150

The processing unit 150 provides various functions of the base station100. The processing unit 150 includes a first transmission processingunit 151, a second transmission processing unit 153, a thirdtransmission processing unit 155, and a notification unit 157. Further,the processing unit 150 may further include other components in additionto these components. That is, the processing unit 150 may performoperations in addition to operations of these components.

Operations of the first transmission processing unit 151, the secondtransmission processing unit 153, the third transmission processing unit155 and the notification unit 157 will be described below in detail.

<4.2. Configuration of Terminal Device>

First, an example of the configuration of the terminal device 200according to an embodiment of the present disclosure will be describedwith reference to FIG. 9. FIG. 9 is a block diagram illustrating theexample of the configuration of the terminal device 200 according to anembodiment of the present disclosure. According to FIG. 9, the terminaldevice 200 includes an antenna unit 210, a radio communication unit 220,a storage unit 230, and a processing unit 240.

(1) Antenna Unit 210

The antenna unit 210 radiates signals output by the radio communicationunit 220 out into space as radio waves. In addition, the antenna unit210 converts radio waves in the space into signals, and outputs thesignals to the radio communication unit 220.

(2) Radio Communication Unit 220

The radio communication unit 220 transmits and receives signals. Forexample, the radio communication unit 220 receives a downlink signalfrom a base station, and transmits an uplink signal to a base station.

(3) Storage Unit 230

The storage unit 230 temporarily or permanently stores a program andvarious data for operation of the terminal device 200.

(4) Processing Unit 240

The processing unit 240 provides various functions of the terminaldevice 200. The processing unit 240 includes an information acquisitionunit 241 and a reception processing unit 243. Note that the processingunit 240 may further include a structural element other than thesestructural elements. That is, the processing unit 240 may performoperation other than the operation of these structural elements.

Operations of the information acquisition unit 241 and the receptionprocessing unit 243 will be described below in detail.

5. FIRST EMBODIMENT

Next, a first embodiment will be described with reference to FIGS. 10 to34.

5.1. Technical Feature

First, technical features of the first embodiment will be described withreference to FIGS. 10 to 16.

(1) Power Layer Interleaving

The base station 100 (the first transmission processing unit 151)generates transmission signal sequences of multiple power layers thathave been multiplexed using power allocation. In addition, for each ofone or more of the multiple power layers, the base station 100 (thesecond transmission processing unit 153) processes a transmission signalsequence of a power layer using an interleaver corresponding to thepower layer. More specifically, the base station 100 (the secondtransmission processing unit 153) interleaves the transmission signalsequence of the power layer using the interleaver corresponding to thepower layer.

The terminal device 200 (the information acquisition unit 241) acquiresan interleaver corresponding to each of at least one of the multiplepower layers. Then, the terminal device 200 (the reception processingunit 241) performs a reception process using the interleavercorresponding to each of the at least one power layer.

Meanwhile, the expression “multiplexing a power layer” has the samemeaning as “multiplexing a signal of the power layer” in thisspecification.

(1) Multiplexing Using Power Allocation

For example, the multiple power layers are power layers that have beenmultiplexed using SPC.

(b) Generation of Transmission Signal Sequence

For example, a transmission signal sequence is an encoded bit sequence(that is, a bit sequence that has been encoded). The base station 100(the first transmission processing unit 151) generates an encoded bitsequence of the multiple power layers.

Specifically, for example, the first transmission processing unit 151performs CRC encoding, FEC encoding, rate matching or the like (as shownin FIG. 2, for example) on each of the multiple power layers to generatethe encoded bit sequence of the power layer.

(c) Interleaver Corresponding to Power Layer

(c-1) First Example: Interleaver Specific to User

As a first example, the transmission signal sequence of the power layeris a transmission signal sequence destined for a user (i e, the terminaldevice 200) and the interleaver corresponding to the power layer is aninterleaver specific to the user. Two or more power layers are notallocated to one user (that is, transmission signal sequences of two ormore layers are not transmission signal sequences to the same user) andonly one power layer is allocated to one user.

For example, the interleaver specific to the user is generated on thebasis of identification information of the user. The identificationinformation may be a radio network temporary identifier (RNTI) of theuser. The interleaver specific to the user may be a deterministicinterleaver (DI) or a linear congruential interleaver (LCI). Of course,the identification information and the interleaver specific to the userare not limited to such examples.

Accordingly, for example, the terminal device 200 can acquire theinterleaver without information about the power layer (e.g., a powerlayer index).

(c-2) Second Example: Interleaver Specific to Power Layer

As a second example, the interleaver corresponding to the power layermay be an interleaver specific to the power layer. The interleaverspecific to the power layer may be generated (for example, by the user)on the basis of information about the power layer (e.g., a power layerindex or an RNTI corresponding to an individual power layer).

Accordingly, for example, the terminal device 200 can easily acquire theinterleaver of each power layer.

(c-3) Others

The interleaver corresponding to the layer may be decided on the basisof an ID of a cell to which the user belongs, the ID of the user, theRNTI of the user, the power layer index, a spatial layer index, a timeindex (e.g., a subframe number or the like) or the like.

Alternatively, the interleaver corresponding to the layer may be decidedon the basis of an independent index for indicating an interleavingpattern. The base station 100 may notify the user (the terminal device200) of the independent index.

(d) One or More Power Layers

(d-1) First Example

For example, the one or more power layers (i.e., power layers which areinterleaving targets) are power layers other than a predetermined numberof power layers among the multiple power layers. For example, thepredetermined number of power layers is a single power layer. That is,for each of the power layers other than the predetermined number ofpower layers (for example, the single power layer) among the multiplepower layers, the base station 100 (the second transmission processingunit 153) interleaves the transmission signal sequence of the powerlayer using the interleaver corresponding to the power layer.

—Power Allocated to Power Layer

For example, the predetermined number of power layers (e.g., the singlepower layer) is a power layer allocated higher transmission power thanthe one or more power layers. That is, the base station 100 (the thirdtransmission processing unit 155) allocates higher transmission power tothe predetermined number of power layers (e.g., the single power layer)and allocates lower transmission power to the one or more power layers.In this regard, a specific example will be described below withreference to FIG. 10.

FIG. 10 is an explanatory diagram for explaining an example of powerallocation of power layers. Referring to FIG. 10, N power layers (thepower layer 0 to a power layer N−1) multiplexed using SPC areillustrated. The base station 100 allocates the power P₀ higher thanpowers P₁ to P_(N−)1 of the power layers 1 to N−1 to the power layer 0.In addition, the base station 100 interleaves transmission signalsequences of the power layers 1 to N−1 but does not interleave atransmission signal sequence of the power layer 0.

For example, a transmission signal sequence of a single power layer(e.g., a single power layer) is a transmission signal sequence destinedfor a legacy terminal that does not support multiplexing/multiple accessusing power allocation (e.g., multiplexing/multiple access using SPC).In other words, the legacy terminal is a terminal device that is notcapable of interference cancellation.

Accordingly, for example, the legacy terminal can decode a desiredsignal included in a multiplexed signal. That is, it is possible tosecure backward compatibility while improving frequency utilizationefficiency.

—Operation of Terminal Device 200 —Reception Process

As described above, the terminal device 200 acquires a deinterleavercorresponding to each of the at least one of the multiple power layersand performs a reception process using the deinterleaver correspondingto each of the at least one power layer.

For example, the at least one power layer is included in the one or morepower layers (i.e., power layers which are interleaving targets) otherthan the predetermined number of power layers (i.e., power layers otherthan the interleaving targets) among the multiple power layers. Theterminal device 200 (the reception processing unit 243) performs thereception process without using the deinterleaver corresponding to eachof the predetermined number of power layers (i.e., the power layersother than the interleaving targets).

Meanwhile, although an example in which the predetermined number ofpower layers is a single power layer has been described, thepredetermined number of power layers is certainly not limited to thisexample. The predetermined number of power layers may be two or morepower layers.

—Determination of Whether Interleaver is Used

For example, the terminal device 200 (the reception processing unit 243)determines a power layer of which transmission signal sequence isprocessed among the multiple power layers using the interleavercorresponding to the power layer (referred to as an “interleaving layer”hereinafter).

For example, the terminal device 200 (the reception processing unit 243)determines a power layer to which higher power is allocated as theinterleaving layer other than a predetermined number of power layers.

Alternatively, the base station 100 may notify the terminal device 200of whether an interleaver is used for a transmission signal sequence ofa power layer, as will be described below. In this case, the terminaldevice 200 (the reception processing unit 243) may determine theinterleaving layer on the basis of notification information from thebase station 100.

(d-2) Second Example

The one or more power layers (i.e., the power layers which areinterleaving targets) may be the multiple power layers. That is, foreach of the multiple power layers, the base station 100 (the secondtransmission processing unit 153) may interleave a transmission signalsequence of a corresponding power layer using an interleavercorresponding to the power layer. In this manner, all of the powerlayers may be interleaving targets.

(e) Interleaving Effect

For example, it is possible to improve decoding accuracy whenmultiplexing/multiple access is performed using power allocationaccording to the aforementioned interleaving.

More specifically, for example, a burst error caused by fadinggeneration is suppressed by interleaving an interference signal.Accordingly, accuracy of decoding of the interference signal increasesand accuracy of interference cancellation also increases, and thusresidual interference decreases. As a result, accuracy of decoding of adesired signal can be improved. In addition, for example, a burst errorcaused by fading generation is suppressed by interleaving a desiredsignal, and accuracy of decoding of the desired signal increases.

Furthermore, in particular, the interleaver used for the interferencesignal differs from the interleaver used for the desired signal, andthus residual interference is dispersed for each interferencecancellation. Accordingly, accuracy of decoding of the desired signal isfurther improved without accumulating residual interference.

A specific example will be described with reference to FIGS. 11 to 14.FIGS. 11 to 14 are explanatory diagrams for explaining examples ofdecoding of a signal according to a first embodiment. Referring to FIG.11, the received power 31 (i.e., received power of a desired signal) ofthe power layer 0 in the terminal device 200A and the received power 33(i.e., received power of an interference signal) of the power layer 1 inthe terminal device 200A are illustrated. In the power layer 0 and thepower layer 1, significant fading is generated in the radio resources37A, 37B, 37C and 37D. However, since the power layer 1 has beeninterleaved, influence of the fading is dispersed by performingdeinterleaving, as shown in FIG. 12. Consequently, a signal of the powerlayer 1 (i.e., an interference signal) is decoded with high accuracy andan interference signal replica is also generated with high accuracy. Inaddition, the interference replica is subtracted from a received signal,and thus the residual interference 35 decreases, as shown in FIG. 13.Furthermore, since the power layer 0 has also been interleaved,influence of the fading is dispersed by performing deinterleaving, asshown in FIG. 14. In addition, since different interleavers are used inthe interleaving of the power layer 0 and the interleaving of the powerlayer 1, the residual interference 35 is dispersed by deinterleaving.

Conversely, when the same interleaver is used for the power layers, theresidual interference is accumulated at the same position instead ofbeing dispersed for each interference cancellation, and thus decodingaccuracy may decrease.

Further, examples of results of simulations related to interleaving willbe described with reference to FIGS. 15 and 16.

FIG. 15 is an explanatory diagram for explaining a result of a firstsimulation related to interleaving. In the first simulation, two powerlayers are multiplexed, 40% of power is allocated to one of the powerlayers and 60% of the power is allocated to the other power layer. FIG.15 shows relationships 41 and 43 between an average signal-to-noiseratio (SNR) and an average block error rate (BLER) for one of the powerlayers as a result of the first simulation. The relationship 41 is arelationship when interleaving is not performed and the relationship 43is a relationship when interleaving is performed. Comparing therelationship 41 when interleaving is not performed with the relationship43 when interleaving is performed, the BLER is lower when interleavingis performed than when interleaving is not performed for the same SNR.Further, from a different point of view, a SNR that is necessary torealize the same BLER is lower when interleaving is performed than wheninterleaving is not performed. In this manner, decoding accuracy isfurther improved by performing interleaving.

FIG. 16 is an explanatory diagram for explaining a result of a secondsimulation related to interleaving. In the second simulation, two powerlayers are multiplexed and the same amount of power (i.e., 50% of thepower) is allocated to both of the power layers. FIG. 16 showsrelationships 45 and 47 between an average SNR and an average BLER forone layer as a result of the second simulation. The relationship 45 is arelationship when interleaving is not performed, and the relationship 47is a relationship when interleaving is performed. Comparing therelationship 45 when interleaving is not performed with the relationship47 when interleaving is performed, even in this example, the BLER islower when interleaving is performed than when interleaving is notperformed for the same SNR. Further, from a different point of view, theSNR that is necessary to realize the same BLER is lower wheninterleaving is performed than when interleaving is not performed. Inthis manner, decoding accuracy is further improved by performinginterleaving.

The simulation results with respect to interleaving have been explainedwith reference to FIGS. 15 and 16. Parameters used in the simulationsare as follows.

TABLE 1 Number of power layers 2 CQI 1 (QPSK) Error correction codeTurbo code (R = ⅓, 8 decoding iterations) Channel estimation FullInterference cancellation Codeword level interference cancellationmethod Propagation path model Extended Typical Urban

Meanwhile, interleaving may have additional advantages. Referring toboth FIGS. 15 and 16, when a power difference between the two powerlayers further decreases, the BLERs for the same SNR further increase.This is because interference cancellation is difficult to perform whenthe power difference between the two power layer decreases. In view ofthis, interleaving can be introduced to improve a degree of freedom forpower allocation and alleviate scheduling restrictions because a certaindegree of BLER is achieved even when the power difference between powerlayers is small due to interleaving being performed. Furthermore, it ispossible to apply SPC multiplexing/multiple access even in anenvironment having a lower SNR by performing interleaving, and thus anarea in which SPC is applicable can be extended through the introductionof interleaving.

(2) Notification to Terminal Device (a) Power Layer

As described above, for each of the one or more of the multiple powerlayers, the base station 100 (the second transmission processing unit153) interleaves the transmission signal sequence of the correspondingpower layer using the interleaver corresponding to the power layer.

For example, the transmission signal sequence of the power layer is atransmission signal sequence destined for a user (i.e., the terminaldevice 200), and the base station 100 (the notification unit 157)notifies the user of the power layer. Accordingly, for example, the usercan be made aware of a power layer of which a signal is transmitted tothe user.

For example, the base station 100 (the notification unit 157) notifiesthe user of the power layer among downlink control information (DCI)destined for the user. The base station 100 transmits the DCI over aphysical downlink control channel (PDCCH). As a specific process, thenotification unit 157 generates DCI which is destined for the user, andindicates the power layer. Accordingly, for example, it is possible todynamically change a power layer for the user for each radio resourceallocation.

(b) Number of Power Layers

For example, the base station 100 (the notification unit 157) notifiesthe user of the number of power layers with respect to the multiplepower layers. That is, the base station 100 (the notification unit 157)notifies the user of the number of multiplexed layers. Accordingly, forexample, the user (i.e., the terminal device 200) can performinterference cancellation.

For example, the base station 100 (the notification unit 157) notifiesthe user of the number of power layers through DCI destined for theuser, a signaling message destined for the user, or system information.For example, the signaling message is a radio resource control (RRC)message, and the system information is a system information block (SIB).As a specific process, the notification unit 157 generates DCI which isdestined for the user and represents the number of power layers, asignaling message which is destined for the user and represents thenumber of power layers or system information representing the number ofpower layers.

(c) Whether Interleaver is Used

The base station 100 (the notification unit 157) may notify the user ofwhether an interleaver is used for a transmission signal sequence (i.e.,the transmission signal sequence of the power layer) destined for theuser. Accordingly, for example, the user can be more easily made awareof whether an interleaver is used.

The base station 100 (the notification unit 157) may notify the user ofwhether an interleaver is used through the DCI destined for the user. Asa specific process, the notification unit 157 may generate DCI which isdestined for the user and represents whether an interleaver is used.Accordingly, it is possible to dynamically change whether an interleaveris used for each radio resource allocation, for example.

Further, the base station 100 (the notification unit 157) may notify theuser of whether an interleaver is used for a transmission signalsequence of each of the multiple power layers including the power layer.Accordingly, the user (i.e., the terminal device 200) can easily be madeaware of whether an interleaver is used for each power layer, forexample. Therefore, interference cancellation can be furtherfacilitated.

(3) Transmission Power Allocated to Power Layer

For example, a transmission signal sequence of a power layer allocatedhigh transmission power among the one or more power layers (i.e., thepower layers which are interleaving targets) is a transmission signalsequence destined for a user with low communication quality. Inaddition, a transmission signal sequence of a power layer allocated lowtransmission power among the one or more power layers is a transmissionsignal sequence destined for a user with high communication quality.

For example, when a transmission signal sequence of a power layer is atransmission signal sequence destined for a user with low communicationquality, the base station 100 (the third transmission processing unit155) allocates high transmission power to the power layer. In addition,when a transmission signal sequence of a power layer is a transmissionsignal sequence destined for a user with high communication quality, thebase station 100 (the third transmission processing unit 155) allocateslow transmission power to the power layer.

As an example, the low communication quality may be high path loss andthe high communication quality may be low path loss. As another example,the low communication quality may be low path gain and the highcommunication quality may be high path gain. As yet another example, thelow communication quality may be a channel quality indicator (CQI) withlow frequency efficiency or a modulation and coding scheme (MCS) withlow frequency efficiency and the high communication quality may be a CQIwith high frequency efficiency or an MCS with high frequency efficiency.As still yet another example, the low communication quality may be a lowsignal-to-interference-plus-noise ratio (SINR) and the highcommunication quality may be a high SINR. Further, the communicationqualities are certainly not limited to such examples.

Accordingly, for example, it is possible to operate a highly functionalreception algorithm (e.g., SIC or the like) with high accuracy to decodea signal of a power layer to which low transmission power has beenallocated.

5.2. Process Flow

Next, examples of processes according to the first embodiment will bedescribed with reference to FIGS. 17 to 28.

(1) Transmission Process

FIG. 17 is a flowchart illustrating an example of a schematic flow of atransmission process of the base station 100 according to the firstembodiment.

The base station 100 (the first transmission processing unit 151)generates an encoded bit sequence by performing error correction codingand rate matching (S301).

When the encoded bit sequence is multiplexed using SPC (S303: YES) andthe encoded bit sequence is not an encoded bit sequence of a power layerto which maximum power is allocated (S305: NO), the base station 100(the second transmission processing unit 153) interleaves the encodedbit sequence (of the power layer) using an interleaver corresponding tothe power layer (S307).

When the encoded bit sequence is not multiplexed using SPC (S303: NO)and the encoded bit sequence is an encoded bit sequence of a power layerto which maximum power is allocated (S305: YES), the base station 100(e.g., the second transmission processing unit 153) scrambles theencoded bit sequence (S311). In this manner, scrambling may be performedwhen interleaving is not performed.

The base station 100 (the third transmission processing unit 155)performs other processes (e.g., modulation, power allocation, etc.) onthe encoded bit sequence (which has been interleaved or scrambled)(S313). Then, the processes end.

(2) Reception Process (a) Reception Process

FIG. 18 is a flowchart illustrating an example of a schematic flow of areception process of the terminal device 200 according to the firstembodiment. For example, the reception process is performed for eachsubframe.

The terminal device 200 (the reception processing unit 243) decodesdownlink control information (DCI) transmitted over a control channel(S321). For example, the control channel is a PDCCH.

When radio resources have been allocated to the terminal device 200(S323: YES) and multiplexing using SPC has been performed (S325: YES),the terminal device 200 performs a decoding process for SPC (S360). Forexample, the decoding process for SPC is interference cancellation (IC),interference suppression (IS), maximum likelihood decoding (MLD) or thelike. Subsequently, the terminal device 200 (the processing unit 240)transmits ACK/NACK to the base station 100 (S327). Then, the processends.

When the radio resources have been allocated to the terminal device 200(S323: YES) and the multiplexing using SPC has not been performed (S325:NO), the terminal device 200 performs decoding process for non-SPC(S340). For example, the decoding process for non-SPC is a decodingprocess for orthogonal multiple access (OMA). Subsequently, the terminaldevice 200 (the processing unit 240) transmits ACK/NACK to the basestation 100 (S327). Then, the process ends.

When the radio resources have not been allocated to the terminal device200 (S323: NO), the process ends.

(b) Decoding Process for Non-SPC

FIG. 19 is a flowchart illustrating an example of a schematic flow of adecoding process for non-SPC. The decoding process for non-SPCcorresponds to step S340 illustrated in FIG. 18.

The terminal device 200 (the reception processing unit 243) performschannel estimation on the basis of a reference signal transmitted by thebase station 100 (S341). For example, the reference signal is acell-specific reference signal (CRS) or a demodulation reference signal(DM-RS). For example, when a precoding matrix is not used (or a specificmatrix (e.g., a unit matrix or a diagonal matrix) is used as theprecoding matrix) while transmission is performed, the terminal device200 performs channel estimation on the basis of a CRS. Conversely, whena precoding matrix selected from a plurality of precoding matrices isused while transmission is performed, the terminal device 200 performschannel estimation on the basis of a DM-RS.

The terminal device 200 (the reception processing unit 243) generates achannel equalization weight and/or a spatial equalization weight on thebasis of a channel estimation result (S343) and performs equalization onreceived signals using the channel equalization weight and/or thespatial equalization weight (S345). The channel equalization weight maybe a linear equalization weight matrix based on a minimum mean squareerror (MMSE) scheme or a linear equalization weight matrix based on thezero forcing (ZF) scheme. As a technique other than linear equalization,maximum likelihood (ML) detection, ML estimation, iterativedetection/iterative cancellation), turbo equalization, or the like maybe used.

The terminal device 200 (the reception processing unit 243) generates alog likelihood ratio (LLR) sequence of a reception side whichcorresponds to the encoded bit sequence on the basis of the result ofthe equalization of the received signals (S347).

When scrambling has been performed on the reception side (S349: YES),the terminal device 200 (the reception processing unit (243) scramblesthe LLR sequence (S351).

The terminal device 200 (the reception processing unit 243) executeserror correction coding on the LLR sequence (which has been scrambled)(S353). For example, the error correction coding is Viterbi decoding,turbo decoding, message passing algorithm decoding or the like.

The terminal device 200 (the reception processing unit 243) performs CRSon the decoded bit sequence (S355). That is, the terminal device 200checks whether decoding has been correctly performed. Then, the processends.

(c) Decoding Process for SPC (First Example: SIC)

(c-1) Whole Process

FIG. 20 is a flowchart illustrating a first example of a schematic flowof a decoding process for SPC. The decoding process for SPC correspondsto step S360 illustrated in FIG. 18. In particular, the first example isan example of a process based on successive interference cancellation(SIC).

The terminal device 200 (the reception processing unit 243) buffers areceived signal (S361).

The terminal device 200 (the reception processing unit 243) selects apower layer to which high power has been allocated from unselected powerlayers as a target layer (S363).

The terminal device 200 (the reception processing unit 243) determines atransmission mode (TM) that has been applied to the target layer (S365).In addition, the terminal device 200 (the reception processing unit 243)determines whether interleaving/scrambling has been performed on thetarget layer (S367). Then, the terminal device 200 performs a decodingprocess for non-SPC on the target layer (S380).

When a signal of the target layer is destined for the terminal device200 (S371: YES), the process ends.

When the signal of the target layer is not destined for the terminaldevice 200 (S371: NO), the terminal device 200 (the reception processingunit 243) performs an interference signal replica generation process onthe target layer (S400). The terminal device 200 (the receptionprocessing unit 243) generates an interference signal replica byperforming the interference signal replica generation process. Then, theterminal device 200 (the reception processing unit 243) subtracts theinterference signal replica from the buffered signal (S373) and buffersthe subtracted signal (S375) again. Then, the process returns to stepS363.

Meanwhile, although only one layer is allocated to one user in theabove-described example, the first embodiment is not limited to thisexample. For example, two or more layers may be allocated to one user.In this case, even when the signal of the target layer is a signaldestined for the terminal device 200 in step S371, the process mayproceed to step S400 instead of ending

In addition, determination of whether interleaving has been performed instep S367 may be performed on the basis of whether the target layer is apower layer with maximum power or whether an interleaver indicated viaDCI is used.

(c-2) Decoding Process for Non-SPC for Target Layer

FIG. 21 is a flowchart illustrating an example of a schematic flow of adecoding process for non-SPC for a target layer. The decoding processfor non-SPC corresponds to step S380 illustrated in FIG. 20.

Meanwhile, no particular difference exists between a description ofsteps S381 to S387 and the description of steps S341 to S347 illustratedin FIG. 19. Accordingly, only steps S389 to S399 will be described.

When interleaving has been performed at a transmission side (S389: YES),the terminal device 200 (the reception processing unit 243)deinterleaves the LLR sequence using a deinterleaver corresponding tothe target layer (S391).

When interleaving has not been performed at the transmission side (S389:NO) but scrambling has been performed at the transmission side (S393:YES), the terminal device 200 (the reception processing unit 243)descrambles the LLR sequence (S395).

The terminal device 200 (the reception processing unit 243) executeserror correction coding on the LLR sequence (which has beendeinterleaved/descrambled) (S397). For example, the error correctioncoding is Viterbi decoding, turbo decoding, MPA decoding or the like.

The terminal device 200 (the reception processing unit 243) performs CRCon the decoded bit sequence (S399). That is, the terminal device 200checks whether decoding has been correctly performed. Then, the processends.

(c-3) Interference Signal Replica Generation Process for Target Layer

FIG. 22 is a flowchart illustrating an example of a schematic flow of aninterference signal replica generation process for a target layer. Theinterference signal replica generation process corresponds to step S400illustrated in FIG. 20.

When the bit sequence of the target layer has been correctly decoded(S401: YES), the terminal device 200 (the reception processing unit 243)acquires the bit sequence (S403) and generates an encoded bit sequenceby performing error correction coding and rate matching on the bitsequence (S405).

Conversely, when the bit sequence of the target layer has not beencorrectly decoded (S401: NO), the terminal device 200 (the receptionprocessing unit 243) acquires an LLR sequence (S407) and performs ratematching on the LLR sequence (S409). The LLR sequence is a sequencegenerated in an error correction decoding process.

Whether the bit sequence of the target layer has been correctly decoded(S401) may be determined on the basis of a result of CRC.

When interleaving has been performed at the transmission side (S411:YES), the terminal device 200 (the reception processing unit 243)interleaves the encoded bit sequence (or the LLR sequence) using theinterleaver corresponding to the target layer (S413).

Conversely, when interleaving has not been performed at the transmissionside (S411: NO) but scrambling has been performed at the transmissionside (S415: YES), the terminal device 200 (the reception processing unit243) scrambles the encoded bit sequence (or the LLR sequence) (S417).

The terminal device 200 (the reception processing unit 243) performsother processes (e.g., modulation, power allocation, and the like) onthe encoded bit sequence (or the LLR sequence) (which has beeninterleaved or scrambled) (S419). Then, the process ends.

Further, for example, soft modulation is performed on the LLR sequenceas another process for the LLR sequence. In the soft modulation, alikelihood of generation of signal point candidates of a modulationsymbol (e.g., BPSK, QPSK, 8 PSK, 16 PSK, 16 QAM, 256 QAM or the like)are calculated using the LLR sequence, and thus expectations of signalpoints of the modulation symbol can be generated. Accordingly, influenceof a bit decoding error in the generation of the interference signalreplica can be reduced.

(d) Decoding Process for SPC (Second Example: PIC)

(d-1) Whole Process

FIG. 23 is a flowchart illustrating an example of a second example of aschematic flow of a decoding process for SPC. The decoding process forSPC corresponds to step S360 illustrated in FIG. 18. Above all, thesecond example is an example of a process based on parallel interferencecancellation (PIC).

The terminal device 200 (the reception processing unit 243) buffers areceived signal (S421).

The terminal device 200 (the reception processing unit 243) determines atransmission mode (TM) that has been applied to each of multiple powerlayers (S423). In addition, the terminal device 200 (the receptionprocessing unit 243) determines whether interleaving/scrambling has beenperformed on each of the multiple power layers (S425). Then, theterminal device 200 performs parallel decoding processes on the multiplepower layers (S440).

When the bit sequence destined for the own device (the terminal device200) has been correctly decoded (S427: YES), the process ends. Inaddition, the bit sequence destined for the own device (the terminaldevice 200) has not been correctly decoded (S427: NO), but the processends even when parallel decoding processes have been performed multipletimes (S429: YES).

When the parallel decoding processes have not been performed multipletimes (S429: NO), the terminal device 200 (the reception processing unit243) performs an interference signal replica generation process (S470).The terminal device 200 (the reception processing unit 243) generates aninterference signal replica by performing the interference signalreplica generation process. Then, the terminal device 200 (the receptionprocessing unit 243) subtracts the interference signal replica from thebuffered signal (S431) and buffers the subtracted signal (S433) again.Then, the process returns to step S440.

Meanwhile, determination of whether interleaving has been performed instep S425 may be performed on the basis of whether the power layer is apower layer with maximum power or whether an interleaver indicated viaDCI is used.

(d-2) Decoding Process

FIG. 24 is a flowchart illustrating an example of a schematic flow ofparallel decoding processes. The parallel decoding processes correspondto step S440 illustrated in FIG. 20.

The terminal device 200 (the reception processing unit 243) performschannel estimation on the basis of a reference signal transmitted by thebase station 100 for each of multiple layers (S441). For example, thereference signal is a CRS or a DM-RS. For example, when a precodingmatrix is not used (or a specific matrix (e.g., a unit matrix or adiagonal matrix) is used as a precoding matrix) while transmission isperformed, the terminal device 200 performs channel estimation on thebasis of the CRS. Conversely, when a precoding matrix selected from aplurality of precoding matrices is used while transmission is performed,the terminal device 200 performs channel estimation on the basis of theDM-RS.

The terminal device 200 (the reception processing unit 243) generates achannel equalization weight and/or a spatial equalization weight on thebasis of a channel estimation result (S443) and performs equalization ona received signal using the channel equalization weight and/or thespatial equalization weight (S445). The channel equalization weight maybe a linear equalization weight matrix based on the MMSE scheme or alinear equalization weight matrix based on the ZF scheme. As a techniqueother than linear equalization, ML detection, ML estimation, iterativeinterference cancellation, turbo equalization or the like may be used.

The terminal device 200 (the reception processing unit 243) selects atarget layer from the multiple layers (S449).

When the bit sequence of the target layer is already correctly decoded(S449: YES), the process ends when all of the power layers are selected(S465: YES), whereas the process returns to step S447 when all of thepower layers are not selected (S465: NO).

When the bit sequence of the target layer is not yet correctly decoded(S449: NO), the terminal device 200 (the reception processing unit 243)generates an LLR sequence of the reception side which corresponds to theencoded bit sequence on the basis of the result of the equalization ofthe received signal (S451).

When interleaving has been performed at the transmission side (S453:YES), the terminal device 200 (the reception processing unit 243)deinterleaves the LLR sequence using a deinterleaver corresponding tothe target layer (S455).

Conversely, when interleaving has not been performed at the transmissionside (S453: NO) but scrambling has been performed at the transmissionside (S457: YES), the terminal device 200 (the reception processing unit243) descrambles the LLR sequence (S459).

The terminal device 200 (the reception processing unit 243) executeserror correction coding on the LLR sequence (which has beendeinterleaved/scrambled) (S461). For example, the error correctiondecoding is Viterbi decoding, turbo decoding, MPA decoding or the like.

The terminal device 200 (the reception processing unit 243) performs CRSon the decoded bit sequence (S463). That is, the terminal device 200checks whether decoding has been correctly performed. Then, the processis ended when all the power layers have been selected (S465: YES)whereas the process returns to step S447 when all of the power layersare not selected (S465: NO).

Meanwhile, although steps S447 to S465 are shown as iterative processesto represent the flowchart, steps S447 to S465 may certainly be executedin parallel for each of the multiple power layers.

(d-3) Generation of Interference Replica

FIG. 25 is a flowchart illustrating an example of a schematic flow of aninterference signal replica generation process. The interference signalreplica generation process corresponds to step S400 illustrated in FIG.20.

The terminal device 200 (the reception processing unit 243) selects atarget layer from multiple power layers (S471).

When a bit sequence of the target layer has been correctly decoded(S473: YES) but an interference signal replica has not been generated onthe basis of the correctly decoded bit sequence of the target layer(S475: NO), the terminal device 200 (the reception processing unit 243)acquires the bit sequence (S477). Then, the terminal device 200 (thereception processing unit 243) performs error correction coding and ratematching on the bit sequence to generate an encoded bit sequence (S449).

When the interference signal replica is already generated on the basisof the correctly decoded bit sequence of the target layer (S475: YES),the process ends when all of the power layers are selected (S497: YES),whereas the process returns to step S471 when all of the power layersare not selected (S497: NO).

When the bit sequence of the target layer has not been correctly decoded(S473: NO), the terminal device 200 (the reception processing unit 243)acquires an LLR sequence (S481) and performs rate matching on the LLRsequence (S483). The LLR sequence is a sequence generated in the errorcorrection decoding process.

Whether the bit sequence of the target layer has been correctly decoded(S473) may be determined on the basis of a result of CRC.

When interleaving has been performed at the transmission side (S485:YES), the terminal device 200 (the reception processing unit 243)interleaves the encoded bit sequence (or the LLR sequence) using aninterleaver corresponding to the target layer (S487)

Conversely, when interleaving has not been performed at the transmissionside (S485: NO) but scrambling has been performed at the transmissionside (S489: YES), the terminal device 200 (the reception processing unit243) scrambles the encoded bit sequence (or the LLR sequence) (S491).

The terminal device 200 (the reception processing unit 243) performsother processes (e.g., modulation, power allocation and the like) on theencoded bit sequence (or the LLR sequence) (which has been interleavedor scrambled) (S493). Then, the terminal device 200 (the receptionprocessing unit 243) buffers the generated interference signal replica(S495). Subsequently, the process ends when all of the power layer areselected (S497: YES), whereas the process retunes to step S471 when allof the power layers are not selected (S497: NO).

(3) Notification (a) First Example

FIG. 26 is a sequence diagram illustrating a first example of aschematic flow of a process including notification from the base station100 to the terminal device 200.

The base station 100 notifies the terminal device 200 of the number ofpower layers through a signaling message destined for the terminaldevice 200 (S501). For example, the base station 100 transmits an RRCmessage which is destined for the terminal device 200 and includes thenumber of power layers. As a specific example, the base station 100transmits the RRC message during or after a random access procedure or ahandover procedure.

The terminal device 200 reports channel state information (CSI) to thebase station 100 (S503).

The base station 100 performs scheduling (S505).

The base station 100 notifies the terminal device 200 of a power layer(i.e., a power layer for transmitting a signal destined for the terminaldevice 200) for the terminal device 200 through DCI destined for theterminal device 200 (S507). For example, the base station 100 transmitsDCI which is destined for the terminal device 200 and indicates thepower layer over a PDCCH.

The base station 100 multiplexes signals destined for a plurality ofterminal devices 200 using SPC (i.e., multiplexes a plurality of powerlayers) to transmit SPC multiplexed signals. For example, the basestation 100 transmits the SPC multiplexed signals over a physicaldownlink shared channel (PDSCH) (S509).

The terminal device 200 performs a reception process and transmitsACK/NACL to the base station 100 (S511).

(b) Second Example

FIG. 27 is a sequence diagram illustrating a second example of aschematic flow of a process including notification from the base station100 to the terminal device 200.

A description of steps 523 to S531 illustrated in FIG. 27 is the same asa description of S503 to S511 illustrated in FIG. 28. Accordingly,redundant descriptions will be omitted and only step S521 will bedescribed herein.

The base station 100 notifies the terminal device 200 of the number ofpower layers through an SIB (S521). For example, the base station 100transmits an SIB indicating the number of power layers.

(c) Third Example

FIG. 28 is a sequence diagram illustrating an example of a third exampleof a schematic flow of a process including notification from the basestation 100 to the terminal device 200.

The terminal device 200 reports channel state information (CSI) to thebase station 100 (S541).

The base station 100 performs scheduling (S543).

The base station 100 notifies the terminal device 200 of the number ofpower layers and a power layer for the terminal device 200 (i.e., apower layer for transmitting a signal destined for the terminal device200) through DCI destined for the terminal device 200 (S507). Forexample, the base station 100 transmits DCI which is destined for theterminal device 200 and indicates the number of power layers and thepower layer over a PDCCH.

The base station 100 multiplexes signals destined for a plurality ofterminal devices 200 using SPC (i.e., multiplexes a plurality of powerlayers) to transmit SPC multiplexed signals. For example, the basestation 100 transmits the SPC multiplexed signals over a PDSCH (S547).

The terminal device 200 performs a reception process and transmitsACK/NACL to the base station 100 (S549).

5.3. First Modified Example

Next, a first modified example of the first embodiment will be describedwith reference to FIGS. 29 to 34.

(1) Technical Feature

As described above, the base station 100 multiplexes power layers usingSPC. Particularly, in the first modified example of the firstembodiment, spatial layers are also multiplexed while power layers aremultiplexed using SPC.

For example, the base station 100 generates transmission signalsequences of multiple power layers multiplexed using power allocationfor each of one or more spatial layers and interleaves the transmissionsignal sequence of the power layer using an interleaver corresponding tothe power layer for each of one or more of the multiple power layers.That is, multiplexing using power allocation is performed in spatiallayers.

(a) Multiplexing Based on Propagation Characteristics

For example, the base station 100 multiplexes spatial layers and powerlayers in consideration of propagation characteristics for a user (theterminal apparatus 200).

(a-1) Precoding Matrix

For example, the base station 100 multiplexes spatial layers and powerlayers in consideration of a precoding matrix used by the user (theterminal device 200).

For example, the transmission signal sequences of the multiple powerlayers are transmission signal sequences destined for multiple users,and the multiple users use the same precoding matrix. That is, thetransmission signal sequences destined for the multiple users (e.g.,multiple terminal devices 200) using the same precoding matrix aretransmitted through different power layers of the same spatial layer.

(a-2) Communication Quality

For example, the base station 100 multiplexes spatial layers and powerlayers in consideration of communication quality of the user (theterminal device 200).

For example, the transmission signal sequences of the multiple powerlayers are transmission signal sequences destined for multiple users,and the multiple users have different communication qualities. That is,the transmission signal sequences destined for the multiple users (e.g.,multiple terminal devices 200) having different communication qualitiesare transmitted through different power layers of the same spatiallayer.

As an example, the different communication qualities may be differentpath losses or different path gains. As another example, the differentcommunication qualities may be different CQIs or different MCSs. As yetanother example, different communication qualities may be differentSINRs. Further, the different communication qualities are certainly notlimited to such examples.

Accordingly, for example, it is possible to prevent allocatedtransmission powers from being equalized in power layers. That is, apower difference between power layers can be obtained and interferencecancellation can be further facilitated.

(a-3) Others

The base station 100 may multiplex spatial layers and power layers inconsideration of other pieces of information. As a specific example, theother pieces of information may be a channel response, an RI or the likebetween the base station 100 and the terminal device 200.

(b) Example of Multiplexing

(b-1) First Example

FIG. 29 is an explanatory diagram for explaining a first example ofmultiplexing spatial layers and power layers. Referring to FIG. 29, amultiplexed spatial layer 0 and a spatial layer 1 and power layers 0 toN−1 multiplexed in each of the spatial layers are illustrated. In thisexample, the same transmission power is allocated to each of the powerlayers 0 to N−1 in the spatial layer 0 and the spatial layer 1. Forexample, in both the spatial layer 0 and the spatial layer 1,transmission power allocated to the power layer 0 is power P₀,transmission power allocated to the power layer 1 is power P₁, andtransmission power allocated to the power layer N−1 is power P_(N−)1.

(b) Example of Multiplexing

(b-2) Second Example

FIG. 30 is an explanatory diagram for explaining a second example ofmultiplexing spatial layers and power layers. Referring to FIG. 30, themultiplexed spatial layer 0, the spatial layer 1, and transmission powerallocated to the power layers 0 to N−1 multiplexed in each of thespatial layers are illustrated. In this example, transmission powersallocated to each of the power layers 0 to N−1 in the spatial layer 0and the spatial layer 1 are not limited to the same transmission powerand may be different. For example, transmission power allocated to thepower layer 0 in the spatial layer 0 is power P₀(0), whereastransmission power allocated to the power layer 0 in the spatial layer 1is power P₀(1) (>P₀(0)). In addition, for example, transmission powerallocated to the power layer N−1 in the spatial layer 0 is powerP_(N−1)(0) whereas transmission power allocated to the power layer N−1in the spatial layer 1 is power P_(N−1)(1) (<P_(N−1)(0)).

(2) Process Flow (a) Selection for Multiplexing

FIG. 31 is a flowchart illustrating an example of a schematic flow of amultiplexing decision process according to the first modified example ofthe first embodiment. For example, each step of the multiplexingdecision process is performed by the processing unit 150 of the basestation 100.

The base station 100 selects a first transmission mode (TM) (S561). Thefirst TM is a TM in which both spatial multiplexing and SPC multiplexingare performed.

When there are no users (the terminal device 200) supporting the firstTM (S563: NO), the base station 100 performs another selection process(S600). Then, the process ends.

When there are users (the terminal device 200) supporting the first TM(S563: YES), the base station 100 sets a set of users supporting thefirst TM as a set A.

When there are no vacancies in spatial layers (S569: NO), the processends. When a vacancy exists in the spatial layers (S569: YES), the basestation 100 select a user a from the set A (S571). Meanwhile, a PMI ofthe user a differs from a PMI of another spatial layer that has beenalready decided.

The base station 100 checks the precoding matrix indicator (PMI) of theuser a (S573). When the set A does not include other users having thesame PMI as the user a (S575: NO), the process returns to step S569.When the set A includes other users having the same PMI as the user a(S575: YES), the base station 100 sets a set of the other users havingthe same PMI as the user a as a set B.

The base station 100 checks a CQI of the user a (S579). When the set Bdoes not include other users having different CQIs from the user a(S581: NO), the process returns to step S569. When the set B includesother users having different CQIs from the user a (S581: YES), the basestation 100 sets a set of the other users having different CQIs from theuser a as a set C (S583).

The base station 100 selects a user c from the set C (S585) and decidesmultiplexing of the user a and the user c using SPC in the same spatiallayer (S587). Then, the base station 100 removes the user a and the userc from the set A (S589) and the process returns to step S569.

As described above, steps S569 to 589 are repeated as long as a vacancyexists in the spatial layers (and as long as a candidate user exists).

Meanwhile, although the CQI is used as communication quality in theabove-described example, an MCS, path loss, path gain, or the like maybe used instead of the CQI.

(b) Other Selection

FIG. 32 is a flowchart illustrating an example of a schematic flow ofanother selection process. The other selection process corresponds tostep S600 illustrated in FIG. 30. For example, each step of the otherselection process is performed by the processing unit 150 of the basestation 100.

The base station 100 selects a second transmission mode (TM) (S601). Thesecond TM is a TM in which spatial multiplexing is not performed whileSPC multiplexing is performed.

When there are no users (the terminal device 200) supporting the secondTM (S603: NO), the base station 100 performs yet another selectionprocess (S605). Then, the process ends.

When there are users (the terminal device 200) supporting the second TM(S603: YES), the base station 100 sets a set of users supporting thesecond TM as a set A (S607). Then the base station 100 selects a user afrom the set A (S609).

The base station 100 checks a CQI of the user a (S611). When a set Bdoes not include any other users having different CQIs from the user a(S613: NO), the process ends. When the set B includes other users havingdifferent CQIs from the user a (S613: YES), the base station 100 sets aset of the other users having different CQls from the user a as a set C(S615).

The base station 100 selects a user c from the set C (S617) and decidesmultiplexing of the user a and the user c using SPC in the same spatiallayer (S619). Then, the base station 100 removes the user a and the userc from the set A (S621) and the process ends.

Meanwhile, although the CQI is used as communication quality in theabove-described example, an MCS, path loss, path gain or the like may beused instead of the CQI.

(c) Decision of Transmission Power

FIG. 33 is a flowchart illustrating an example of a schematic flow of atransmission power decision process according to the first modifiedexample of the first embodiment. For example, each step of thetransmission power decision process is performed by the processing unit150 of the base station 100.

The base station 100 compares CQIs of a user a and a user c havingtransmission signals mapped to the same spatial layer (S631).

When the CQI of the user a has lower frequency utilization efficiencythan the CQI of the user c (S636: YES), the base station 100 (theprocessing unit 150) decides to allocate high transmission power to apower layer of the user a and allocate low transmission power to a powerlayer of the user c (S635). Then, the process ends. Thereafter, the basestation 100 (the third transmission processing unit 155) allocates thehigh transmission power to a power layer through which a signal destinedfor the user a is transmitted and allocates the low transmission powerto a power layer though which a signal destined for the user c istransmitted.

When the CQI of the user a has higher frequency utilization efficiencythan the CQI of the user c (S636: NO), the base station 100 (theprocessing unit 150) decides to allocate low transmission power to thepower layer of the user a and allocate high transmission power to thepower layer of the user c (S637). Thereafter, the base station 100 (thethird transmission processing unit 155) allocates the low transmissionpower to the power layer through which the signal destined for the usera is transmitted and allocates the high transmission power to the powerlayer through which the signal destined for the user c is transmitted.

Meanwhile, although the CQI is used as communication quality in theabove-described example, an MCS, path loss, path gain or the like may beused instead of the CQI.

(d) Transmission Process

FIG. 34 is a flowchart illustrating an example of a schematic flow of atransmission process of the base station 100 according to the firstmodified example of the first embodiment.

The base station (the first transmission processing unit 151) performserror correction coding and rate matching to generate an encoded bitsequence (S651).

When the encoded bit sequence is multiplexed using SPC in a spatiallayer (S653: YES) and the encoded bit sequence is not an encoded bitsequence of a power layer to which maximum power is allocated in thespatial layer (S655: NO), the base station (the second transmissionprocessing unit 153) interleaves the encoded bit sequence (of a powerlayer) using an interleaver corresponding to the power layer (S657).

If the encoded bit sequence is not multiplexed using SPC in a spatiallayer (S653: NO) and the encoded bit sequence is the encoded bitsequence of the power layer to which the maximum power is allocated inthe spatial layer (S655: YES), when scrambling is performed (S59: YES),the base station 100 (e.g., the second transmission processing unit 153)scrambles the encoded bit sequence (S661). In this manner, scramblingmay be performed when interleaving is not performed.

The base station 100 (e.g., the second transmission processing unit 153)performs other processes (e.g., modulation, power allocation and thelike) on the encoded bit sequence (which has been interleaved orscrambled) (S663). Then, the process ends.

Meanwhile, although the CQI is used as communication quality in theabove-described example, an MCS, path loss, path gain, or the like maybe used instead of the CQI.

5.4. Second Modified Example

Next, a second modified example of the first embodiment will bedescribed.

In the aforementioned example of the first embodiment, for each of oneor more of the multiple power layers, the base station 100 (the secondtransmission processing unit 153) processes the transmission signalsequence of the power layer using the interleaver corresponding to thepower layer. In addition, the terminal device 200 (the informationacquisition unit 241) performs a reception process using thedeinterleaver corresponding to each of at least one of the multiplepower layers.

Meanwhile, in the second modified example, particularly, a scrambler anda descrambler corresponding to a power layer are used instead of aninterleaver and a deinterleaver corresponding to the power layer. Thatis, for each of one or more of multiple power layers, the base station100 (the second transmission processing unit 153) processes atransmission signal sequence of the power layer using a scramblercorresponding to the power layer. In addition, the terminal device 200(the information acquisition unit 241) performs a reception processusing a scrambler corresponding to each of the at least one of themultiple power layers.

Accordingly, for example, effects equal or similar to those obtainedwhen an interleaver and a deinterleaver corresponding to the power layerare used are achieved. That is, decoding accuracy whenmultiplexing/multiple access using power allocation is performed can befurther improved.

Meanwhile, there are no special differences between a description of thesecond modified example and the description of the aforementionedexamples (including the first modified example) of the first embodimentexcept that “interleaver” is replaced by “scrambler,” “interleave” isreplaced by “scramble,” “interleaving” is replaced by “scrambling,”“deinterleaver” is replaced by “descrambler,” “deinterleave” is replacedby “descramble,” and “deinterleaving” is replaced by “descrambling.”Accordingly, redundant descriptions will be omitted herein.

As an example, when an i^(-th) bit of a scrambled input bit sequence ofa user u (or power layer u) is set to b_(u)(i) and an i^(-th) bit of asequence for scrambling is set to c_(u)(i), an i^(-th) bit b_(u) ⁻(i) ofa scrambled output bit sequence is expressed as follows.

{tilde over (b)} _(u)(i)=(b _(u)(i)+c _(u)(i))mod 2  [Math. 22]

That is, if the bit c_(u)(i) is 0, the i^(-th) bit b_(u) ^(˜)(i) of theoutput bit sequence is the same as the i^(-th) bit h_(u)(i) of the inputbit sequence. Conversely, if the bit c_(u)(i) is 1, the i^(-th) bitb_(u) ^(˜)(i) of the output bit sequence is a bit obtained by reversing(0 to 1 or 1 to 0) the i^(-th) bit b_(u)(i) of the input bit sequence.

The sequence for scrambling may be said to be a scrambling pattern.Further, the input bit sequence and the output bit sequence may be saidto be an input bit sequence and an output bit sequence of a scrambler.

Although a specific example of scrambling has been described, a reverseprocess of scrambling is obviously performed as descrambling.

6. SECOND EMBODIMENT

Next, a second embodiment will be described with reference to FIGS. 35to 38.

<1. Technical Features>

First, technical features of the second embodiment will be describedwith reference to FIG. 35.

(1) Layer Phase Rotation

The base station 100 (the first transmission processing unit 151)generates transmission signal sequences of multiple power layersmultiplexed using power allocation. Then, for each of one or more of themultiple power layer, the base station 100 (the second transmissionprocessing unit 153) processes the transmission signal sequence of thepower layer using a phase coefficient corresponding to the power layer.More specifically, the base station 100 (the second transmissionprocessing unit 153) rotates a phase of the transmission signal sequenceof the power layer using the phase coefficient corresponding to thepower layer.

The terminal device 200 (the information acquisition unit 241) acquiresa phase coefficient corresponding to each of at least one of themultiple power layers. Then, the terminal device 200 (the receptionprocessing unit 241) performs a reception process using the phasecoefficient corresponding to each of the at least one power layer.

Meanwhile, for example, the transmission signal sequence is atransmitted data signal sequence, and the base station 100 (the secondtransmission processing unit 153) does not rotate a phase of a referencesignal using a phase coefficient corresponding to a power layer.

(a) Multiplexing Using Power Allocation

For example, the multiple power layers are power layers multiplexedusing SPC.

(b) Generation of Transmission Signal Sequence

For example, the transmission signal sequences are symbol sequences. Thebase station 100 (the first transmission processing unit 151) generatessymbol sequences of the multiple power layers.

Specifically, for example, the first transmission processing unit 151performs CRC coding, FEC coding, rate matching, scrambling/interleaving,modulation, layer mapping, power allocation or the like (as illustratedin FIGS. 1 and 2, for example) for each of the multiple power layers togenerate a symbol sequence of the power layer.

(c) Phase Coefficient Corresponding to Layer

(c-2) First Example: Phase Coefficient Specific to Power Layer

As a first example, a phase coefficient corresponding to a power layeris a phase coefficient specific to the power layer. In this case, forexample, the phase coefficient specific to the power layer is generated(for example, by the user) on the basis of information about the powerlayer (e.g., an index of the power layer).

Accordingly, for example, the terminal device 200 can easily acquire aphase coefficient of each power layer.

(c-2) Second Example: Phase Coefficient Specific to User

As a second example, the transmission signal sequence of the power layeris a transmission signal sequence destined for a user (i.e., theterminal device 200), and the phase coefficient corresponding to thepower layer may be a phase coefficient specific to the user. Two or morepower layers are not allocated to one user (i.e., transmission signalsequences of two or more layers are not transmission signal sequences ofthe same user) and only one power layer may be allocated to one user.

The phase coefficient specific to the user may be generated (forexample, by the user) on the basis of identification information of theuser. The identification information may be an RNTI of the user.

Accordingly, for example, the terminal device 200 can acquire a phasecoefficient without information about a power layer (e.g., an index ofthe power layer).

(c-3) Example of Phase Coefficient

—Transmission Side

For example, a phase coefficient of a transmission side (i.e., a phasecoefficient used by the base station 100) is a coefficient as follows.

$\begin{matrix}{{\exp \left( {j\frac{2\; \pi \; p}{N_{P}}} \right)}{\exp \left( {j\frac{2\; \pi \; l}{N_{SL}}} \right)}{\exp \left( {j\frac{2\; \pi \; k}{N_{SC}}} \right)}{\exp \left( {j\frac{2\; \pi \; t}{N_{SYM}}} \right)}} & \left\lbrack {{Math}.\mspace{11mu} 23} \right\rbrack\end{matrix}$

N_(P) is the number of power layers, N_(SL) is the number of spatiallayers, N_(SC) is the number of subcarriers, N_(SYM) is the number ofsymbols per subframe or slot, p is a power layer index, l is a spatiallayer index, k is a subcarrier index, and t is a symbol index.

—Reception Side

For example, a phase coefficient of a reception side (i.e., a phasecoefficient used by the terminal device 200) is a coefficient asfollows.

$\begin{matrix}{{\exp \left( {{- j}\frac{2\; \pi \; p}{N_{P}}} \right)}{\exp \left( {{- j}\frac{2\; \pi \; l}{N_{SL}}} \right)}{\exp \left( {{- j}\frac{2\; \pi \; k}{N_{SC}}} \right)}{\exp \left( {{- j}\frac{2\; \pi \; t}{N_{SYM}}} \right)}} & \left\lbrack {{Math}.\mspace{11mu} 24} \right\rbrack\end{matrix}$

Accordingly, phase rotation (i.e., rotation for returning to an originalphase) which is reverse of phase rotation of the transmission side isexecuted.

(d) One or More Layers

There are no special differences in the description of the one or morelayers between the first embodiment and the second embodiment.Accordingly, redundant descriptions will be omitted herein.

(e) Example of Phase Rotation

(e-1) First Example

As a first example, the phase coefficient corresponding to the powerlayer is a frequency shift amount corresponding to the power layer.

More specifically, for example, the phase of a signal (symbol) of apower layer is rotated (i.e., the signal of the power layer is shiftedin a frequency direction) as follows.

ŝ _(i,u)(t)=s _(i,u)(t)exp(−j2πtΔ _(T) F _(shift,i,u))  [Math. 25]

S_(t,u)(t) is a signal sample (symbol) destined for a user u in a cell iat a time t before phase rotation, and ŝ_(i,u)(t) is a signal sampleafter phase rotation. In addition, Δ_(T) is a sample spacing. Further,F_(shift,i,u) is a phase coefficient and, more specifically, a frequencyshift amount.

(e-2) Second Example

As a second example, the phase coefficient corresponding to the powerlayer may be a time shift amount corresponding to the power layer.

More specifically, the phase of a signal (symbol) of the power layer maybe rotated (i.e., a signal of the power layer may be shifted in a timedirection) as follows.

Ŝ _(i,u)(k)=S _(i,u)(k)exp(−j2πkΔ _(F) T _(shift,i,u))

S_(i,u)(k) is a symbol of a frequency k (e.g., subcarrier k) beforephase rotation (while being symbol destined for the user u in the celli) and ŝ_(i,u)(k) is a sample after phase rotation. In addition, A_(F)is a frequency spacing (e.g., subcarrier spacing). Further,T_(shift,i,u) is a phase coefficient and, more specifically, a timeshift amount.

Meanwhile, when the base station 100 performs an inverse Fouriertransform, the phase of the signal (symbol) of the power layer may berotated (i.e., the signal of the power layer may be shifted in the timedirection) as follows.

$\begin{matrix}{{{\hat{s}}_{i,u}(t)} + {\frac{1}{\sqrt{K}}{\sum\limits_{k = 0}^{K - 1}\; {{S_{i,u}(k)}\exp \left\{ {j\; 2\; \pi \; k\; {\Delta_{F}\left( {t - T_{{shift},i,u}} \right)}} \right\}}}}} & \left\lbrack {{Math}.\mspace{11mu} 27} \right\rbrack\end{matrix}$

ŝ_(i,u)(t) is a signal sample (symbol) destined for the user u in thecell i at a time t after phase rotation.

(f) Effect of Phase Rotation

According to the aforementioned phase rotation, for example, decodingaccuracy can be further improved when multiplexing/multiple access usingpower allocation is performed.

More specifically, for example, fading (e.g., fading of frequencyselectivity and/or time selectivity) is equally generated in multiplepower layers multiplexed using SPC, as described above. That is,channels identically change in the multiple power layers. Accordingly,it is possible to pseudo-delay a channel variation for each of the powerlayers by differently performing phase rotation for the power layers.For example, channel variation can be shifted in the frequency directionin a frequency region through linear shifting in the time direction.Accordingly, for example, significant fading is generated at differentpositions in each of the power layers, and thus a pseudo spatialdiversity effect can be obtained and interference cancellation anddecoding accuracy can be improved.

A specific example will be described with reference to FIG. 35. FIG. 35is an explanatory diagram for explaining an example of a channelvariation shift in the frequency direction. Referring to FIG. 35,received power 31 of the power layer 0 and received power 33 of thepower layer 1 before a shift with respect to the power layer 1 in thefrequency direction, and the received power 31 of the power layer 0 andthe received power 33 of the power layer 1 after the shift areillustrated. Although significant fading occurs at a frequency 38 forthe power layer 0 and the power layer 1 before the shift, a position atwhich the significant fading occurs for the power layer 1 ispseudo-shifted from the frequency 38 to a position 39 after the shift.Consequently, the significant fading occurs at different positions forthe power layer 0 and the power layer 1, and thus interferencecancellation and decoding accuracy can be improved.

(2) Notification to Terminal Device (a) Power Layer

As described above, for each of the one or more of the multiple powerlayers, the base station 100 (the second transmission processing unit153) rotates a phase of a transmission signal sequence of a power layerusing a phase coefficient corresponding to the power layer.

For example, the transmission signal sequence of the power layer is atransmission signal sequence destined for a user (i.e., the terminaldevice 200) and the base station 100 (the notification unit 157)notifies the user of the power layer. Accordingly, for example, the usercan be made aware of a power layer through which a signal destined forthe user is transmitted.

For example, the base station 100 (the notification unit 157) notifiesthe user of the power layer through DCI destined for the user. The basestation 100 transmits the DCI over a PDCCH. As a specific process, thenotification unit 157 generates DCI which is destined for the user andindicates the power layer. Accordingly, for example, it is possible todynamically change the power layer for the user for each radio resourceallocation.

(b) Number of Power Layers

There are no special differences in the description of notification ofthe number of power layers between the first embodiment and the secondembodiment. Accordingly, redundant descriptions will be omitted herein.

(c) Whether Phase Coefficient is Used

The base station 100 (the notification unit 157) may notify the user ofwhether a phase coefficient is used for the transmission signal sequence(i.e., the transmission signal sequence of the power layer) destined forthe user. Accordingly, for example, the user can be easily made aware ofwhether a phase coefficient is used.

The base station 100 (the notification unit 157) may notify the user ofwhether a phase coefficient is used through the DCI destined for theuser. As a specific process, the notification unit 157 may generate DCIwhich is destined for the user and indicates whether a phase coefficientis used. Accordingly, for example, it is possible to dynamically changewhether to use a phase coefficient for each radio resource allocation.

Further, the base station 100 (the notification unit 157) may notify theuser of whether phase coefficients are used for transmission signalsequences of each of the multiple power layers including the powerlayer. Accordingly, for example, the user (i.e., the terminal device200) can be easily made aware of whether a phase coefficient is used foreach of the power layers. Accordingly, interference cancellation can befurther facilitated.

(3) Transmission Power Allocated to Power Layer

There are no special differences in the description of power allocatedto a power layer between the first embodiment and the second embodiment.Accordingly, redundant descriptions will be omitted herein.

<6.2. Process Flow>

Next, an example of a process according to the second embodiment will bedescribed with reference to FIGS. 36 and 37.

(1) Transmission Process

FIG. 36 is a flowchart illustrating an example of a schematic flow of atransmission process of the base station 100 according to the secondembodiment.

The base station 100 (the first transmission processing unit 151)performs error correction coding and rate matching to generate anencoded bit sequence (S671). Further, the base station 100 (the firsttransmission processing unit 151) executes other processes (modulation,power allocation, and the like) on the encoded bit sequence to generatea symbol sequence (S673).

When the symbol sequence is multiplexed using SPC (S675: YES) and thesymbol sequence is not a symbol sequence of a power layer to whichmaximum power is allocated (S677: NO), the base station 100 (the secondtransmission processing unit 153) rotates a phase of the symbol sequence(of a power layer) using a phase coefficient corresponding to the powerlayer (S679).

The base station 100 (the third transmission processing unit 155)precodes the symbol sequence (after phase rotation) (S681). Then, theprocess ends.

(2) Reception Process

FIG. 37 is a flowchart illustrating an example of a schematic flow of areception process of the terminal device 200 according to the secondembodiment.

When multiplexing using SPC has been performed (S691: YES) and phaserotation has been performed for a power layer while transmission isperformed (S693: YES), the terminal device 200 rotates the phase of thesymbol sequence of the power layer using the phase coefficientcorresponding to the power layer (S695). This rotation is a reverse ofthe rotation performed when transmission is performed. Then, the processends.

When multiplexing using SPC has not been performed (S691: NO) and phaserotation has not been performed (S693: NO), the process ends withoutphase rotation.

<6.3. Modified Example>

Next, a modified example of the second embodiment will be described withreference to FIG. 38.

As described above, the base station 100 multiplexes power layers usingSPC. Particularly, in the modified example of the second embodiment,spatial layers are multiplexed while power layers are multiplexed usingSPC.

For example, the base station 100 generates transmission signalsequences of multiple power layers multiplexed using power allocationfor each of one or more spatial layers and rotates a phase of atransmission signal sequence of a power layer using a phase coefficientcorresponding to the power layer for each of one or more of the multiplepower layers. That is, multiplexing using power allocation is performedin spatial layers. A specific example will be described with referenceto FIG. 38.

FIG. 38 is an explanatory diagram for explaining an example of a processin a case of a combination of spatial multiplexing and multiplexingusing power allocation. Referring to FIG. 38, a process 41 and a process43 in one spatial layer are illustrated. The process 41 is phaserotation, and the process 43 is precoding. More specifically, in theprocess 41, for each of power layers 0 to N_(P)−1, a phase of a symbolsequence of the power layer is rotated using a phase coefficientcorresponding to the power layer. That is, phase rotation is performeddifferently for the power layers. In addition, in the process 43,precoding for a symbol sequence is performed using a precoding matrixcorresponding to the spatial layer. That is, common precoding isperformed in the spatial layer. Further, different precoding matricesare used in two or more spatial layers. In addition, for example, asymbol of each power layer is a data signal symbol.

(a) Multiplexing Based on Propagation Characteristics.

For example, the base station 100 multiplexes spatial layers and powerlayers in consideration of propagation characteristics for the user (theterminal device 200). There are no special differences in thedescription of this fact between the first modified example of the firstembodiment and the modified example of the second embodiment.Accordingly, redundant descriptions will be omitted herein.

(b) Example of Multiplexing

There are no special differences in the description of an example ofmultiplexing between the first modified example and the first embodimentof the modified example of the second embodiment. Accordingly, redundantdescriptions will be omitted herein.

7. APPLICATION EXAMPLE

The technology of the present disclosure can be applied to variousproducts. The base station 100 may be realized as any type of evolvednode B (eNB), for example, a macro eNB, a small eNB, or the like. Asmall eNB may be an eNB that covers a smaller cell than a macro cell,such as a pico eNB, a micro eNB, or a home (femto) eNB. Alternatively,the base station 100 may be realized as another type of base stationsuch as a node B or a base transceiver station (BTS). The base station100 may include a main body that controls radio communication (alsoreferred to as a base station device) and one or more remote radio heads(RRHs) disposed in a different place from the main body. In addition,various types of terminals to be described below may operate as the basestation 100 by temporarily or semi-permanently executing the basestation function. Furthermore, at least some of constituent elements ofthe base station 100 may be realized in a base station device or amodule for a base station device.

In addition, the terminal device 200 may be realized as, for example, amobile terminal such as a smartphone, a tablet personal computer (PC), anotebook PC, a portable game terminal, a portable/dongle type mobilerouter, or a digital camera, or an in-vehicle terminal such as a carnavigation device. In addition, the terminal device 200 may be realizedas a terminal that performs machine-to-machine (M2M) communication (alsoreferred to as a machine type communication (MTC) terminal).Furthermore, at least some of constituent elements of the terminaldevice 200 may be realized in a module mounted in such a terminal (forexample, an integrated circuit module configured in one die).

<7.1. Application Example with Regard to Base Station>

(First Application Example)

FIG. 39 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station device 820. Each antenna 810 and the base stationdevice 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the base station device 820 to transmit and receive radiosignals. The eNB 800 may include the multiple antennas 810, asillustrated in FIG. 39. For example, the multiple antennas 810 may becompatible with multiple frequency bands used by the eNB 800. AlthoughFIG. 39 illustrates the example in which the eNB 800 includes themultiple antennas 810, the eNB 800 may also include a single antenna810.

The base station device 820 includes a controller 821, a memory 822, anetwork interface 823, and a radio communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of a higher layer of the base station device 820. Forexample, the controller 821 generates a data packet from data in signalsprocessed by the radio communication interface 825, and transfers thegenerated packet via the network interface 823. The controller 821 maybundle data from multiple base band processors to generate the bundledpacket, and transfer the generated bundled packet. The controller 821may have logical functions of performing control such as radio resourcecontrol, radio bearer control, mobility management, admission control,and scheduling. The control may be performed in corporation with an eNBor a core network node in the vicinity. The memory 822 includes RANI andROM, and stores a program that is executed by the controller 821, andvarious types of control data (such as a terminal list, transmissionpower data, and scheduling data).

The network interface 823 is a communication interface for connectingthe base station device 820 to a core network 824. The controller 821may communicate with a core network node or another eNB via the networkinterface 823. In this case, the eNB 800 may be connected to a corenetwork node or another eNB through a logical interface (e.g. 51interface or X2 interface). The network interface 823 may also be awired communication interface or a radio communication interface forradio backhaul. If the network interface 823 is a radio communicationinterface, the network interface 823 may use a higher frequency band forradio communication than a frequency band used by the radiocommunication interface 825.

The radio communication interface 825 supports any cellularcommunication scheme such as Long Term Evolution (LTE) and LTE-Advanced,and provides radio connection to a terminal positioned in a cell of theeNB 800 via the antenna 810. The radio communication interface 825 maytypically include, for example, a baseband (BB) processor 826 and an RFcircuit 827. The BB processor 826 may perform, for example,encoding/decoding, modulating/demodulating, andmultiplexing/demultiplexing, and performs various types of signalprocessing of layers (such as L1, medium access control (MAC), radiolink control (RLC), and a packet data convergence protocol (PDCP)). TheBB processor 826 may have a part or all of the above-described logicalfunctions instead of the controller 821. The BB processor 826 may be amemory that stores a communication control program, or a module thatincludes a processor and a related circuit configured to execute theprogram. Updating the program may allow the functions of the BBprocessor 826 to be changed. The module may be a card or a blade that isinserted into a slot of the base station device 820. Alternatively, themodule may also be a chip that is mounted on the card or the blade.Meanwhile, the RF circuit 827 may include, for example, a mixer, afilter, and an amplifier, and transmits and receives radio signals viathe antenna 810.

The radio communication interface 825 may include the multiple BBprocessors 826, as illustrated in FIG. 39. For example, the multiple BBprocessors 826 may be compatible with multiple frequency bands used bythe eNB 800. The radio communication interface 825 may include themultiple RF circuits 827, as illustrated in FIG. 39. For example, themultiple RF circuits 827 may be compatible with multiple antennaelements. Although FIG. 39 illustrates the example in which the radiocommunication interface 825 includes the multiple BB processors 826 andthe multiple RF circuits 827, the radio communication interface 825 mayalso include a single BB processor 826 or a single RF circuit 827.

In the eNB 800 shown in FIG. 39, one or more structural elementsincluded in the processing unit 150 (the first transmission processingunit 151, the second transmission processing unit 153, the thirdtransmission processing unit 155 and/or the reporting unit 157)described with reference to FIG. 8 may be implemented by the radiocommunication interface 825. Alternatively, at least some of theseconstituent elements may be implemented by the controller 821. As anexample, a module which includes a part (for example, the BB processor826) or all of the radio communication interface 825 and/or thecontroller 821 may be mounted in eNB 800, and the one or more structuralelements may be implemented by the module. In this case, the module maystore a program for causing the processor to function as the one or morestructural elements (i.e., a program for causing the processor toexecute operations of the one or more structural elements) and mayexecute the program. As another example, the program for causing theprocessor to function as the one or more structural elements may beinstalled in the eNB 800, and the radio communication interface 825 (forexample, the BB processor 826) and/or the controller 821 may execute theprogram. As described above, the eNB 800, the base station device 820,or the module may be provided as a device which includes the one or morestructural elements, and the program for causing the processor tofunction as the one or more structural elements may be provided. Inaddition, a readable recording medium in which the program is recordedmay be provided.

In addition, in the eNB 800 shown in FIG. 39, the radio communicationunit 120 described with reference to FIG. 8 may be implemented by theradio communication interface 825 (for example, the RF circuit 827).Moreover, the antenna unit 110 may be implemented by the antenna 810. Inaddition, the network communication unit 130 may be implemented by thecontroller 821 and/or the network interface 823.

(Second Application Example)

FIG. 40 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station device 850, and an RRH 860. Each antenna 840 and the RRH860 may be connected to each other via an RF cable. The base stationdevice 850 and the RRH 860 may be connected to each other via a highspeed line such as an optical fiber cable.

Each of the antennas 840 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the RRH 860 to transmit and receive radio signals. The eNB 830may include the multiple antennas 840, as illustrated in FIG. 40. Forexample, the multiple antennas 840 may be compatible with multiplefrequency bands used by the eNB 830. Although FIG. 40 illustrates theexample in which the eNB 830 includes the multiple antennas 840, the eNB830 may also include a single antenna 840.

The base station device 850 includes a controller 851, a memory 852, anetwork interface 853, a radio communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are the same as the controller 821, the memory822, and the network interface 823 described with reference to FIG. 39.

The radio communication interface 855 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and provides radiocommunication to a terminal positioned in a sector corresponding to theRRH 860 via the RRH 860 and the antenna 840. The radio communicationinterface 855 may typically include, for example, a BB processor 856.The BB processor 856 is the same as the BB processor 826 described withreference to FIG. 39, except the BB processor 856 is connected to the RFcircuit 864 of the RRH 860 via the connection interface 857. The radiocommunication interface 855 may include the multiple BB processors 856,as illustrated in FIG. 40. For example, the multiple BB processors 856may be compatible with multiple frequency bands used by the eNB 830.Although FIG. 40 illustrates the example in which the radiocommunication interface 855 includes the multiple BB processors 856, theradio communication interface 855 may also include a single BB processor856.

The connection interface 857 is an interface for connecting the basestation device 850 (radio communication interface 855) to the RRH 860.The connection interface 857 may also be a communication module forcommunication in the above-described high speed line that connects thebase station device 850 (radio communication interface 855) to the RRH860.

The RRH 860 includes a connection interface 861 and a radiocommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(radio communication interface 863) to the base station device 850. Theconnection interface 861 may also be a communication module forcommunication in the above-described high speed line.

The radio communication interface 863 transmits and receives radiosignals via the antenna 840. The radio communication interface 863 maytypically include, for example, the RF circuit 864. The RF circuit 864may include, for example, a mixer, a filter, and an amplifier, andtransmits and receives radio signals via the antenna 840. The radiocommunication interface 863 may include multiple RF circuits 864, asillustrated in FIG. 40. For example, the multiple RF circuits 864 maysupport multiple antenna elements. Although FIG. 40 illustrates theexample in which the radio communication interface 863 includes themultiple RF circuits 864, the radio communication interface 863 may alsoinclude a single RF circuit 864.

In the eNB 830 shown in FIG. 40, one or more structural elementsincluded in the processing unit 150 (the first transmission processingunit 151, the second transmission processing unit 153, the thirdtransmission processing unit 155 and/or the reporting unit 157)described with reference to FIG. 8 may be implemented by the radiocommunication interface 855 and/or the radio communication interface863. Alternatively, at least some of these constituent elements may beimplemented by the controller 851. As an example, a module whichincludes a part (for example, the BB processor 856) or all of the radiocommunication interface 855 and/or the controller 851 may be mounted ineNB 830, and the one or more structural elements may be implemented bythe module. In this case, the module may store a program for causing theprocessor to function as the one or more structural elements (i.e., aprogram for causing the processor to execute operations of the one ormore structural elements) and may execute the program. As anotherexample, the program for causing the processor to function as the one ormore structural elements may be installed in the eNB 830, and the radiocommunication interface 855 (for example, the BB processor 856) and/orthe controller 851 may execute the program. As described above, the eNB830, the base station device 850, or the module may be provided as adevice which includes the one or more structural elements, and theprogram for causing the processor to function as the one or morestructural elements may be provided. In addition, a readable recordingmedium in which the program is recorded may be provided.

In addition, in the eNB 830 shown in FIG. 40, the radio communicationunit 120 described, for example, with reference to FIG. 8 may beimplemented by the radio communication interface 863 (for example, theRF circuit 864). Moreover, the antenna unit 110 may be implemented bythe antenna 840. In addition, the network communication unit 130 may beimplemented by the controller 851 and/or the network interface 853.

<7.2. Application Example with Regard to Terminal Device>

(First Application Example)

FIG. 41 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which the technology of the presentdisclosure may be applied. The smartphone 900 includes a processor 901,a memory 902, a storage 903, an external connection interface 904, acamera 906, a sensor 907, a microphone 908, an input device 909, adisplay device 910, a speaker 911, a radio communication interface 912,one or more antenna switches 915, one or more antennas 916, a bus 917, abattery 918, and an auxiliary controller 919.

The processor 901 may be, for example, a CPU or a system on a chip(SoC), and controls functions of an application layer and another layerof the smartphone 900. The memory 902 includes RAM and ROM, and stores aprogram that is executed by the processor 901, and data. The storage 903may include a storage medium such as a semiconductor memory and a harddisk. The external connection interface 904 is an interface forconnecting an external device such as a memory card and a universalserial bus (USB) device to the smartphone 900.

The camera 906 includes an image sensor such as a charge coupled device(CCD) and a complementary metal oxide semiconductor (CMOS), andgenerates a captured image. The sensor 907 may include a group ofsensors such as a measurement sensor, a gyro sensor, a geomagneticsensor, and an acceleration sensor. The microphone 908 converts soundsthat are input to the smartphone 900 to audio signals. The input device909 includes, for example, a touch sensor configured to detect touchonto a screen of the display device 910, a keypad, a keyboard, a button,or a switch, and receives an operation or an information input from auser. The display device 910 includes a screen such as a liquid crystaldisplay (LCD) and an organic light-emitting diode (OLED) display, anddisplays an output image of the smartphone 900. The speaker 911 convertsaudio signals that are output from the smartphone 900 to sounds.

The radio communication interface 912 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and performs radiocommunication. The radio communication interface 912 may typicallyinclude, for example, a BB processor 913 and an RF circuit 914. The BBprocessor 913 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for radio communication. Meanwhile,the RF circuit 914 may include, for example, a mixer, a filter, and anamplifier, and transmits and receives radio signals via the antenna 916.The radio communication interface 912 may also be a one chip module thathas the BB processor 913 and the RF circuit 914 integrated thereon. Theradio communication interface 912 may include the multiple BB processors913 and the multiple RF circuits 914, as illustrated in FIG. 41.Although FIG. 41 illustrates the example in which the radiocommunication interface 912 includes the multiple BB processors 913 andthe multiple RF circuits 914, the radio communication interface 912 mayalso include a single BB processor 913 or a single RF circuit 914.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 912 may support another type of radiocommunication scheme such as a short-distance wireless communicationscheme, a near field communication scheme, and a radio local areanetwork (LAN) scheme. In that case, the radio communication interface912 may include the BB processor 913 and the RF circuit 914 for eachradio communication scheme.

Each of the antenna switches 915 switches connection destinations of theantennas 916 among multiple circuits (such as circuits for differentradio communication schemes) included in the radio communicationinterface 912.

Each of the antennas 916 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the radio communication interface 912 to transmit and receiveradio signals. The smartphone 900 may include the multiple antennas 916,as illustrated in FIG. 41. Although FIG. 41 illustrates the example inwhich the smartphone 900 includes the multiple antennas 916, thesmartphone 900 may also include a single antenna 916.

Furthermore, the smartphone 900 may include the antenna 916 for eachradio communication scheme. In that case, the antenna switches 915 maybe omitted from the configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the external connection interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the radio communication interface 912, and the auxiliarycontroller 919 to each other. The battery 918 supplies power to blocksof the smartphone 900 illustrated in FIG. 41 via feeder lines, which arepartially shown as dashed lines in the figure. The auxiliary controller919 operates a minimum necessary function of the smartphone 900, forexample, in a sleep mode.

In the smartphone 900 shown in FIG. 41, the information acquisition unit241 and/or the reception processing unit 243 described with reference toFIG. 9 may be implemented by the radio communication interface 912.Alternatively, at least some of these constituent elements may beimplemented by the processor 901 or the auxiliary controller 919. As anexample, a module which includes a part (for example, the BB processor913) or all of the radio communication interface 912, the processor 901and/or the auxiliary controller 919 may be mounted in the smartphone900, and the information acquisition unit 241 and/or the receptionprocessing unit 243 may be implemented by the module. In this case, themodule may store a program for causing the processor to function as theinformation acquisition unit 241 and/or the reception processing unit243 (i.e., a program for causing the processor to execute operations ofthe information acquisition unit 241 and/or the reception processingunit 243) and may execute the program. As another example, the programfor causing the processor to function as the information acquisitionunit 241 and/or the reception processing unit 243 may be installed inthe smartphone 900, and the radio communication interface 912 (forexample, the BB processor 913), the processor 901 and/or the auxiliarycontroller 919 may execute the program. As described above, thesmartphone 900 or the module may be provided as a device which includesthe information acquisition unit 241 and/or the reception processingunit 243, and the program for causing the processor to function as theinformation acquisition unit 241 and/or the reception processing unit243 may be provided. In addition, a readable recording medium in whichthe program is recorded may be provided.

In addition, in the smartphone 900 shown in FIG. 41, the radiocommunication unit 220 described, for example, with reference to FIG. 9may be implemented by the radio communication interface 912 (forexample, the RF circuit 914). Moreover, the antenna unit 210 may beimplemented by the antenna 916.

(Second Application Example)

FIG. 42 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device 920 to which the technology ofthe present disclosure may be applied. The car navigation device 920includes a processor 921, a memory 922, a global positioning system(GPS) module 924, a sensor 925, a data interface 926, a content player927, a storage medium interface 928, an input device 929, a displaydevice 930, a speaker 931, a radio communication interface 933, one ormore antenna switches 936, one or more antennas 937, and a battery 938.

The processor 921 may be, for example, a CPU or a SoC, and controls anavigation function and another function of the car navigation device920. The memory 922 includes RAM and ROM, and stores a program that isexecuted by the processor 921, and data.

The GPS module 924 uses GPS signals received from a GPS satellite tomeasure a position (such as latitude, longitude, and altitude) of thecar navigation device 920. The sensor 925 may include a group of sensorssuch as a gyro sensor, a geomagnetic sensor, and a barometric sensor.The data interface 926 is connected to, for example, an in-vehiclenetwork 941 via a terminal that is not shown, and acquires datagenerated by the vehicle, such as vehicle speed data.

The content player 927 reproduces content stored in a storage medium(such as a CD and a DVD) that is inserted into the storage mediuminterface 928. The input device 929 includes, for example, a touchsensor configured to detect touch onto a screen of the display device930, a button, or a switch, and receives an operation or an informationinput from a user. The display device 930 includes a screen such as aLCD or an OLED display, and displays an image of the navigation functionor content that is reproduced. The speaker 931 outputs sounds of thenavigation function or the content that is reproduced.

The radio communication interface 933 supports any cellularcommunication scheme such as LET and LTE-Advanced, and performs radiocommunication. The radio communication interface 933 may typicallyinclude, for example, a BB processor 934 and an RF circuit 935. The BBprocessor 934 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for radio communication. Meanwhile,the RF circuit 935 may include, for example, a mixer, a filter, and anamplifier, and transmits and receives radio signals via the antenna 937.The radio communication interface 933 may be a one chip module havingthe BB processor 934 and the RF circuit 935 integrated thereon. Theradio communication interface 933 may include the multiple BB processors934 and the multiple RF circuits 935, as illustrated in FIG. 42.Although FIG. 42 illustrates the example in which the radiocommunication interface 933 includes the multiple BB processors 934 andthe multiple RF circuits 935, the radio communication interface 933 mayalso include a single BB processor 934 or a single RF circuit 935.

Furthermore, in addition to a cellular communication scheme, the radiocommunication interface 933 may support another type of radiocommunication scheme such as a short-distance wireless communicationscheme, a near field communication scheme, and a radio LAN scheme. Inthat case, the radio communication interface 933 may include the BBprocessor 934 and the RF circuit 935 for each radio communicationscheme.

Each of the antenna switches 936 switches connection destinations of theantennas 937 among multiple circuits (such as circuits for differentradio communication schemes) included in the radio communicationinterface 933.

Each of the antennas 937 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the radio communication interface 933 to transmit and receiveradio signals. The car navigation device 920 may include the multipleantennas 937, as illustrated in FIG. 42. Although FIG. 42 illustratesthe example in which the car navigation device 920 includes the multipleantennas 937, the car navigation device 920 may also include a singleantenna 937.

Furthermore, the car navigation device 920 may include the antenna 937for each radio communication scheme. In that case, the antenna switches936 may be omitted from the configuration of the car navigation device920.

The battery 938 supplies power to blocks of the car navigation device920 illustrated in FIG. 42 via feeder lines that are partially shown asdashed lines in the figure. The battery 938 accumulates power suppliedform the vehicle.

In the car navigation device 920 shown in FIG. 42, the informationacquisition unit 241 and/or the reception processing unit 243 describedwith reference to FIG. 9 may be implemented by the radio communicationinterface 933. Alternatively, at least some of these constituentelements may be implemented by the processor 921. As an example, amodule which includes a part (for example, the BB processor 934) or allof the radio communication interface 933 and/or the processor 921 may bemounted in the car navigation device 920, and the informationacquisition unit 241 and/or the reception processing unit 243 may beimplemented by the module. In this case, the module may store a programfor causing the processor to function as the information acquisitionunit 241 and/or the reception processing unit 243 (i.e., a program forcausing the processor to execute operations of the informationacquisition unit 241 and/or the reception processing unit 243) and mayexecute the program. As another example, the program for causing theprocessor to function as the information acquisition unit 241 and/or thereception processing unit 243 may be installed in the car navigationdevice 920, and the radio communication interface 933 (for example, theBB processor 934) and/or the processor 921 may execute the program. Asdescribed above, the car navigation device 920 or the module may beprovided as a device which includes the information acquisition unit 241and/or the reception processing unit 243, and the program for causingthe processor to function as the information acquisition unit 241 and/orthe reception processing unit 243 may be provided. In addition, areadable recording medium in which the program is recorded may beprovided.

In addition, in the car navigation device 920 shown in FIG. 42, theradio communication unit 220 described, for example, with reference toFIG. 9 may be implemented by the radio communication interface 933 (forexample, the RF circuit 935). Moreover, the antenna unit 210 may beimplemented by the antenna 937.

The technology of the present disclosure may also be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of thecar navigation device 920, the in-vehicle network 941, and a vehiclemodule 942. In other words, the in-vehicle system (or a vehicle) 940 maybe provided as a device which includes the information acquisition unit241 and/or the reception processing unit 243. The vehicle module 942generates vehicle data such as vehicle speed, engine speed, and troubleinformation, and outputs the generated data to the in-vehicle network941.

8. CONCLUSION

So far, devices and processes according to embodiments of the presentdisclosure have been described with reference to FIGS. 1 to 42.

According to an embodiment of the present disclosure, the base station100 includes the first transmission processing unit 151, which generatestransmission signal sequences of multiple power layers multiplexed usingpower allocation, and the second transmission processing unit 153, whichprocesses a transmission signal sequence of a corresponding power layerfor each of one or more of the multiple power layers using aninterleaver or a phase coefficient corresponding to the power layer.

According to an embodiment of the present disclosure, the terminaldevice 200 includes the information acquisition unit 241, which acquiresa deinterleaver or a phase coefficient corresponding to each of at leastone of multiple power layers multiplexed using power allocation, and thereception processing unit 243, which performs a reception process usingthe deinterleaver or the phase coefficient corresponding to each of theat least one power layer.

Accordingly, for example, it is possible to further improve decodingaccuracy when multiplexing/multiple access using power allocation isperformed.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples. A personskilled in the art may find various alterations and modifications withinthe scope of the appended claims, and it should be understood that theywill naturally come under the technical scope of the present disclosure.

For example, although examples using techniques of existing systems suchas LTE, LTE-A, and the like have been described with respect tocommunication of the base station and the terminal device, the presentdisclosure is certainly not limited to such examples. A technique of anew system may be used. As an example, generation of a transmissionsignal sequence by the first transmission processing unit of the basestation may be performed by a technique of a new system.

In addition, for example, although the base station is a transmissiondevice and the terminal device is a reception device with respect tomultiplexing using power allocation, the present disclosure is notlimited to such an example. The transmission device and the receptiondevice may be other devices.

In addition, processing steps in processes of the present specificationmay not necessarily be executed in, for example, a time series manner inthe order described in the flowcharts or sequence diagrams. Theprocessing steps in the processes may also be executed in, for example,a different order from the order described in the flowcharts or sequencediagrams, or may be executed in parallel.

In addition, a computer program for causing a processor (for example, aCPU, a DSP, or the like) provided in a device of the presentspecification (for example, a base station, a base station device or amodule for a base station device, or a terminal device or a module for aterminal device) to function as a constituent element of the device (forexample, the first transmission processing unit and the secondtransmission processing unit, or the information acquisition unit 241and the reception processing unit 243, or the like) (in other words, acomputer program for causing the processor to execute operations of theconstituent element of the device) can also be created. In addition, arecording medium in which the computer program is recorded may also beprovided. Further, a device that includes a memory in which the computerprogram is stored and one or more processors that can execute thecomputer program (a base station, a base station device or a module fora base station device, or a terminal device or a module for a terminaldevice) may also be provided. In addition, a method including anoperation of the constituent element of the device (for example, thefirst transmission processing unit and the second transmissionprocessing unit, or the information acquisition unit 241 and thereception processing unit 243, or the like) is also included in thetechnology of the present disclosure.

Further, the effects described in this specification are merelyillustrative or exemplified effects, and are not limitative. That is,with or in the place of the above effects, the technology according tothe present disclosure may achieve other effects that are clear to thoseskilled in the art from the description of this specification.

Additionally, the present technology may also be configured as below.

(1)

An apparatus including:

a first transmission processing unit that generates transmission signalsequences of multiple power layers that are to be multiplexed usingpower allocation; and

a second transmission processing unit that processes a transmissionsignal sequence of a power layer using an interleaver, a scrambler, or aphase coefficient corresponding to the power layer for each of one ormore of the multiple power layers.

(2)

The apparatus according to (1), in which the second transmissionprocessing unit interleaves the transmission signal sequence of thepower layer using the interleaver corresponding to the power layer.

(3)

The apparatus according to (2), in which the transmission signalsequence of the power layer is a transmission signal sequence destinedfor a user, and

the interleaver corresponding to the power layer is an interleaverspecific to the user.

(4)

The apparatus according to (2), in which the interleaver correspondingto the power layer is an interleaver specific to the power layer.

(5)

The apparatus according to (1), in which the second transmissionprocessing unit rotates a phase of the transmission signal sequence ofthe power layer using the phase coefficient corresponding to the powerlayer.

(6)

The apparatus according to (5), in which the transmission signalsequence is a sequence of data signals to be transmitted, and

the second transmission processing unit does not rotate a phase of areference signal using the phase coefficient corresponding to the powerlayer.

(7)

The apparatus according to any one of (1) to (6), in which the one ormore of the power layers are power layers other than a predeterminednumber of power layers among the multiple power layers.

(8)

The apparatus according to (7), in which the predetermined number ofpower layers are power layers to which higher transmission power isallocated than the one or more power layers.

(9)

The apparatus according to (7) or (8), in which the predetermined numberof power layers is a single power layer.

(10)

The apparatus according to any one of (1) to (6), in which the one ormore power layers are the multiple power layers.

(11)

The apparatus according to any one of (1) to (10), in which atransmission signal sequence of a power layer to which highertransmission power is allocated among the one or more power layers is atransmission signal sequence destined for a user having lowercommunication quality, and

a transmission signal sequence of a power layer to which lowertransmission power is allocated among the one or more power layers is atransmission signal sequence destined for a user having highercommunication quality.

(12)

The apparatus according to any one of (1) to (11), in which thetransmission signal sequence of the power layer is a transmission signalsequence destined for a user, and

the apparatus further includes a notification unit that notifies theuser of the power layer.

(13)

The apparatus according to (12), in which the notification unit notifiesthe user of the power layer through downlink control informationdestined for the user.

(14)

The apparatus according to (12) or (13), in which the notification unitnotifies the user of the number of power layers with respect to themultiple power layers.

(15)

The apparatus according to (14), in which the notification unit notifiesthe user of the number of power layers through downlink controlinformation destined for the user, a signaling message destined for theuser, or system information.

(16)

The apparatus according to any one of (12) to (15), in which thenotification unit notifies the user of whether the interleaver, thescrambler, or the phase coefficient is used for the transmission signalsequence destined for the user.

(17)

The apparatus according to (16), in which the notification unit notifiesthe user of whether the interleaver, the scrambler, or the phasecoefficient is used through downlink control information destined forthe user.

(18)

An apparatus including:

an acquisition unit that acquires a deinterleaver, a descrambler or aphase coefficient corresponding to each of at least one power layeramong multiple power layers that are to be multiplexed using powerallocation; and

a reception processing unit that performs a reception process using thedeinterleaver, the descrambler or the phase coefficient corresponding toeach of the at least one power layer.

(19)

The apparatus according to (18), in which the at least one power layeris included in one or more power layers other than a predeterminednumber of power layers among the multiple power layers, and

the reception processing unit performs a reception process without usinga deinterleaver, a descrambler or a phase coefficient corresponding toeach of the predetermined number of power layers.

(20)

The apparatus according to (18) or (19), in which the receptionprocessing unit determines a power layer of which transmission signalsequence is to be processed using an interleaver, a scrambler or a phasecoefficient corresponding to the power layer among the multiple powerlayers.

(21)

The apparatus according to (1), in which the second transmissionprocessing unit scrambles the transmission signal sequence of the powerlayer using the scrambler corresponding to the power layer.

(22)

The apparatus according to (21), in which the transmission signalsequence of the power layer is a transmission signal sequence destinedfor a user, and

the scrambler corresponding to the power layer is a scrambler specificto the user.

(23)

The apparatus according to (21), in which the scrambler corresponding tothe power layer is a scrambler specific to the power layer.

(24)

The apparatus according to any one of (1) to (17), in which theapparatus is a base station, a base station apparatus for the basestation, or a module for the base station apparatus.

(25)

The apparatus according to any one of (18) to (20), in which theapparatus is a terminal device or a module for the terminal device.

(26)

The apparatus according to any one of (1) to (25), in which the multiplepower layers are layers that are to be multiplexed using SPC.

(27)

A method that is performed by a processor, the method including:

generating transmission signal sequences of multiple power layers thatare to be multiplexed using power allocation; and

processing a transmission signal sequence of a power layer using aninterleaver, a scrambler, or a phase coefficient corresponding to thepower layer for each of one or more of the multiple power layers.

(28)

A program causing a processor to execute:

generating transmission signal sequences of multiple power layers thatare to be multiplexed using power allocation; and

processing a transmission signal sequence of a power layer using aninterleaver, a scrambler, or a phase coefficient corresponding to thepower layer for each of one or more of the multiple power layers.

(29)

A readable storage medium having a program stored therein, the programcausing a processor to execute:

generating transmission signal sequences of multiple power layers thatare to be multiplexed using power allocation; and

processing a transmission signal sequence of a power layer using aninterleaver, a scrambler, or a phase coefficient corresponding to thepower layer for each of one or more of the multiple power layers.

(30)

A method that is performed by a processor, the method including:

acquiring a deinterleaver, a descrambler or a phase coefficientcorresponding to each of at least one power layer among multiple powerlayers that are to be multiplexed using power allocation; and

performing a reception process using the deinterleaver, the descrambleror the phase coefficient corresponding to each of the at least one powerlayer.

(31)

A program causing a processor to execute:

acquiring a deinterleaver, a descrambler or a phase coefficientcorresponding to each of at least one power layer among multiple powerlayers that are to be multiplexed using power allocation; and

performing a reception process using the deinterleaver, the descrambleror the phase coefficient corresponding to each of the at least one powerlayer.

(32)

A readable storage medium having a program stored therein, the programcausing a processor to execute:

acquiring a deinterleaver, a descrambler or a phase coefficientcorresponding to each of at least one power layer among multiple powerlayers that are to be multiplexed using power allocation; and

performing a reception process using the deinterleaver, the descrambleror the phase coefficient corresponding to each of the at least one powerlayer.

REFERENCE SIGNS LIST

-   1 system-   100 base station-   101 cell-   151 first transmission processing unit-   153 second transmission processing unit-   155 third transmission processing unit-   157 notification unit-   200 terminal device-   241 information acquisition unit-   243 reception processing unit

1. An apparatus comprising: a first transmission processing unit thatgenerates transmission signal sequences of multiple power layers thatare to be multiplexed using power allocation; and a second transmissionprocessing unit that processes a transmission signal sequence of a powerlayer using an interleaver, a scrambler, or a phase coefficientcorresponding to the power layer for each of one or more of the multiplepower layers.
 2. The apparatus according to claim 1, wherein the secondtransmission processing unit interleaves the transmission signalsequence of the power layer using the interleaver corresponding to thepower layer.
 3. The apparatus according to claim 2, wherein thetransmission signal sequence of the power layer is a transmission signalsequence destined for a user, and the interleaver corresponding to thepower layer is an interleaver specific to the user.
 4. The apparatusaccording to claim 2, wherein the interleaver corresponding to the powerlayer is an interleaver specific to the power layer.
 5. The apparatusaccording to claim 1, wherein the second transmission processing unitrotates a phase of the transmission signal sequence of the power layerusing the phase coefficient corresponding to the power layer.
 6. Theapparatus according to claim 5, wherein the transmission signal sequenceis a sequence of data signals to be transmitted, and the secondtransmission processing unit does not rotate a phase of a referencesignal using the phase coefficient corresponding to the power layer. 7.The apparatus according to claim 1, wherein the one or more of the powerlayers are power layers other than a predetermined number of powerlayers among the multiple power layers.
 8. The apparatus according toclaim 7, wherein the predetermined number of power layers are powerlayers to which higher transmission power is allocated than the one ormore power layers.
 9. The apparatus according to claim 7, wherein thepredetermined number of power layers is a single power layer.
 10. Theapparatus according to claim 1, wherein the one or more power layers arethe multiple power layers.
 11. The apparatus according to claim 1,wherein a transmission signal sequence of a power layer to which highertransmission power is allocated among the one or more power layers is atransmission signal sequence destined for a user having lowercommunication quality, and a transmission signal sequence of a powerlayer to which lower transmission power is allocated among the one ormore power layers is a transmission signal sequence destined for a userhaving higher communication quality.
 12. The apparatus according toclaim 1, wherein the transmission signal sequence of the power layer isa transmission signal sequence destined for a user, and the apparatusfurther comprises a notification unit that notifies the user of thepower layer.
 13. The apparatus according to claim 12, wherein thenotification unit notifies the user of the power layer through downlinkcontrol information destined for the user.
 14. The apparatus accordingto claim 12, wherein the notification unit notifies the user of thenumber of power layers with respect to the multiple power layers. 15.The apparatus according to claim 14, wherein the notification unitnotifies the user of the number of power layers through downlink controlinformation destined for the user, a signaling message destined for theuser, or system information.
 16. The apparatus according to claim 12,wherein the notification unit notifies the user of whether theinterleaver, the scrambler, or the phase coefficient is used for thetransmission signal sequence destined for the user.
 17. The apparatusaccording to claim 16, wherein the notification unit notifies the userof whether the interleaver, the scrambler, or the phase coefficient isused through downlink control information destined for the user.
 18. Anapparatus comprising: an acquisition unit that acquires a deinterleaver,a descrambler or a phase coefficient corresponding to each of at leastone power layer among multiple power layers that are to be multiplexedusing power allocation; and a reception processing unit that performs areception process using the deinterleaver, the descrambler or the phasecoefficient corresponding to each of the at least one power layer. 19.The apparatus according to claim 18, wherein the at least one powerlayer is included in one or more power layers other than a predeterminednumber of power layers among the multiple power layers, and thereception processing unit performs a reception process without using adeinterleaver, a descrambler or a phase coefficient corresponding toeach of the predetermined number of power layers.
 20. The apparatusaccording to claim 18, wherein the reception processing unit determinesa power layer of which transmission signal sequence is to be processedusing an interleaver, a scrambler or a phase coefficient correspondingto the power layer among the multiple power layers.